Reading Quiz

Question 1:

Compare an object when it is near the surface of the earth and when it is near the surface of the moon. Where is the force of gravity on the object larger: the earth or the moon, or is it the same in both places? Where is the weight of the object larger (earth/moon/same)? Where is the mass of the object larger (earth/moon/same)? Were any of these questions redundant (briefly explain)?

Answer:

The force of gravity acting on an object and the object's weight are the same thing. The force of gravity at the surface of the the moon is weaker. However, the mass of the object remains unchanged.
  1. The force of gravity on the object would be larger on the earth than on the moon since the earth is more massive. The weight of the object would also be larger on the earth since w=mg, and if g is larger on earth, that means that weight would also be larger. (Therefore since weight is based on the force of gravity there is a direct relationship between the two, so the first two questions can be considered redundant.) The mass of the object would be the same however on both the earth and the moon, because mass does not change.
  2. The force of gravity on an object is much larger on the earth. The weight of the object is also much larger on the earth, because weight is directly affected by the force of gravity (it is gravity times mass). However, the mass of the object is the same on both places. The first two questions were redundant because the force of gravity and the weight of an object are related.
  3. The force of gravity is larger near the earth's surface. The weight of the object is larger on the earth. The mass of the object remains constant on the moon and the earth. The first two were redundant, because weight is a measure of how large the force of gravity is at that location.
  4. The force of gravity on the object is greater near the surface of the earth. The weight of the object is also larger near the surface of the earth, but the mass of the object remains the same. The first two questions are redundant because weight and the force of gravity are proportinal.
  5. The force of gravity on the earth is much greater than on the moon because the earth's mass is many times larger. The weight of an object is larger on the earth because weight is mass times acceleration due to gravity. While the object's mass is constant, the acceleration due to gravity changes because the earth has many times more gravity than the moon. The first two questions were relatively redundant because force of gravity and weight are interrelated because weight is a measurement of mass times acceleration due to gravity and the difference in the forces of gravity on the moon and earth modify the object's weight.
  6. The force of gravity is much stronger on earth than near the moon, and as a result, the weight of an object is much larger on the earth than on the moon. Weight depends on the force of gravity, so these questions tell us the same thing. However, the mass of the two objects is the same no matter where they are.
  7. The force of Gravity is greater on Earth than on the Moon. Weight of the object is less on the Moon than it is on Earth. The mass of the object is also greater on Earth than it is on the Moon. Yes, the questions of weight and mass were redundant because weight is exactly proportional to an objects mass.
  8. Because gravity weakens with distance, the force of gravity on an object is larger on the earth than on the moon. The weight of the object is also larger on the earth than on the moon. Because weight is how hard gravity pulls on the object, these two questions are redundant; wherever the force of gravity on the object is larger, the object's weight will be larger as well. The mass of the object is the same on the earth and on the moon because mass is not dependent on gravity.
  9. The force of gravity on the object and the weight of the object are both larger on the earth but the mass is the same in both places. The first and second questions were similar because the weight of an object is directly proportional to the force of gravity.
  10. The force of gravity is larger on the earth than the moon. Since gravity is a component of weight, the weight of an object is also larger on the earth. The mass of the object is equal on both surfaces. The first two questions were redundant because the object's weight is equal to its mass times the acceleration of gravity. Wherever there is a stronger gravitational force, the weight of the object will be larger.
  11. The force of gravity of an object is the object's weight so the first two quetions are redundant. The object's weight, and therefore it force of gravity, is larger on the earth. The mass of an object would be the same no matter if it was on the earth or the moon.
  12. The force of gravity on the object is larger when it is near the earth. The weight is also more when it is closer to the earth. The mass of the object is the same. Weight and Gravity are more or less the same thing. Weight measures the effect gravity has on an object.
  13. The force of gravity on the earth would be about 6 times larger than on the moon. The weight of an object on the earth would be about 6 times larger than the object's weight on the moon. The object's mass would be the same in both places. No, they were all unique because mass and gravity are two unique variables, were as weight is the product of gravity and mass.
  14. The force of gravity on the object will be larger on the earth. The weight of the object will also be larger on the earth. The mass of the object however will be the same regardless of whether in is on the moon or the earth. The question regarding weight was somewhat redundant, since weight is the product of mass and acceleration due to gravity, and since the mass remains constant and gravity of the earth is greater than that of the moon, the product of those two (the weight), will consequently also be larger on the earth than on the moon.
  15. The force of gravity near the moon is much weaker than the force of gravity near the earth. The weight of an object on the moon is also less than the weight of an object on the earth. The mass of an object on the moon and the earth is the same. The two questions about weight and force of gravity could be considered redundant because the force of gravity directly affects the weight of an object.
  16. There is a stronger force of gravity on the Earth than the moon. The weight is is more on the Earth. The mass is the same on both the Earth and moon. No the questions were not redundant. Mass, gravity and weight are all separate things. The weight is equal to mass times gravitational force.
  17. The force of gravity on the object is larger on the earth. This downward force that gravity creates is called weight; thus, weight is also larger on the earth. (That question was a bit redundant.) The mass of an object, however, is not affected by gravity; it is the same on both the earth and the moon.
  18. The force of gravity on the object is larger on the earth than on the moon because gravity weakens with distance. As an object travels farther from the earth, the less gravitational effect the earth will have on it. The weight of the object will be less near the surface of the moon than its weight near the surface of the earth. The mass of the object will remain the same on either surface. The 1st and 2nd questions were redundant because weight is the measure of how hard gravity pulls on an object (gravitational force).
  19. The force of gravity is greater when on the surface of the earth because it is a larger object and therefore has a greater force of gravity. The weight of the same object would be greater on the earth because it weight is a product of mass multiplied by the downward acceleration of gravity and that acceleration is greater on the earth. The mass of the object stays the same. The first two questions were because they were both based on the differences in force of gravity between the earth and moon.
  20. The force of gravity is larger on Earth. This is because the force of gravity weakens with distance, and the moon is obviously far away. The weight of an object is larger on the Earth. The mass is also larger on Earth. These questions all had the same answer, because the closer an object is to the center of gravity (on the earth) the harder the force of gravity pulls on the object (the weight). The weight is directly proportional to the mass, and since the moon is far away from the earth, its gravitational pull is weaker.
  21. The force of gravity on an object would be larger on earth and there would be virtually no gravitational force near the moon. Therefore, the weight of the object would be larger on earth than on the moon. However, the mass of the object would stay the same whether on earth or on the moon because mass doesn't depend on gravity. These questions were very similar to the first "Check Your Understanding" question in the book.
  22. The force of gravity on an object is larger on the earth. THe wieght of the object is therefore larger on the earth since it will have a larger force of gravity. The mass of the object is the same on both the moon and the earth. These questions were not redundant becuase they all had different answers and all explained our understanding and changes in mass, weight, and force of gravity on the earth and moon.
  23. The force of gravity on the object is larger on earth. The weight of the object is larger on earth (exactly 6 times the weight on the moon). The mass of the object is is exactly proportional to the object's weight, so since the weight is greater on earth than on the moon the mass is also larger on earth.

Question 2:

Consider a situation where we can neglect the effects of air resistance. You throw a ball straight up into the air. On its way up, what happens to the direction of the ball's motion? On its way up, what happens to the speed of the ball? At the very top of the ball's motion, what is its speed? At the very top of the ball's motion, what is its acceleration?

Answer:

You threw the ball straight up, so on its way up, its direction remains up. However, the ball slows down, so its speed decreases. At the very top of the ball's motion, its speed is zero. At the very top of the ball's motion, it is still affected by gravity, so it still has the acceleration due to gravity: 9.8 m/s2.
  1. The direction of the ball's motion remains upward on its way up, but its speed decreases down to zero at the very top of its motion. Throughout the ball's travel upward and then downward, the acceleration is constant, 9.8m/s2 (the acceleration due to gravity).
  2. The direction of the ball's motion is that it goes up, stops, and then comes back down. On the way up, the speed of the ball slows down until at the very top, it has a velocity of zero. The ball's acceleration is the same throughout the throw (It is 9.8 m/s2 toward the earth).
  3. The direction of the ball's motion is upward, and doesn't change. The speed of the ball will decrease as it goes higher. At the top of the motion, the speed is zero. It's acceleration is also zero.
  4. the ball travels straight up, comes to a stop, and then travels straight down, on the way up the speed of the ball is slowing at a constant acceleration to a stop, speed at the top = 0 m/s , acceleration = -9.8 m/s/s
  5. The direction of a ball's motion is changing as it rises into the air when thrown. The speed of the ball decreases because gravity pulls it towards the ground and makes the distance it can cover in one second decrease. At the very top of the ball's motion, its speed is 0m/s because there is no change in distance or time at that split second of reaching the top of its arc. Its acceleration is also 0m/s because it there is no change in direction or speed.
  6. As you throw the ball up into the air, its direction is up, but the speed decreases due to the pull of gravity. The ball slows down, and at the very top of its flight, its velocity at that instant is zero. The ball then continues accelerating downward at 9.8 m/s due to gravity, and begins traveling in the downward direction.
  7. The ball's direction continues upward until the force on the ball can no longer counter the pull from gravity, acceleration due to gravity. The speed of the ball slowly dissapates as it rises. It's speed is zero. It's acceleration is 9.8m/s2
  8. On the way up, the ball is accelerating downward at 9.8 m/s^2. On the way up, the velocity of the ball decreases. At the very top of the ball's motion, it has a velocity of zero. At the very top of it's motion, the ball has an acceleration of -9.8 m/s^2.
  9. Nothing happens to the direction of the ball's motion and on the way up the speed decreases. At the very top the speed is 0 and the acceleration is equal to the force of gravity.
  10. The direction of the ball doesnt change as it is going up, but the speed steadily decreases. At the top of the ball's motion, it's speed is 0 m/s, and it's acceleration is still -9/8 m/s2.
  11. On the way up, the ball's direction is up and the speed decreases as it goes up. At the top of its motion, its speed is 0 and its acceleration is 9.8m/s^2.
  12. The ball moves in a straight line path. The speed of the ball decreases on its way up. At the very top, the ball's speed is 0 m/s. The acceleration at the top of its motion is -9.8 meters/seconds squared.
  13. The direction of the ball is constant in a straight-upwards direction until it reaches its peak and then moves in exactly the opposite direction downwards. The speed of the ball declines steadily on its way up because the force of gravity counteracts the initial force that set the ball in motion and causes the ball to cover less space per second until it eventually stops momentarily. At the very to of the ball's motion its speed is 0 because at that moment it is not travelling at all. At the top of its motion the ball's acceleration is also 0 for a brief second because it is hot traveling in any direction for a split-second.
  14. On its way up, the direction of the ball's motion is in the upward/positive direction, the speed decreases on its way up. At the top of the ball's motion, it's spped is actually 0 m/s where the ball is at a moment of rest. At this point, the ball's acceleration is still -9.8 m/s, since accerationg due to gravity has not changed.
  15. On the way up the ball's direction remains the same. It continues upward untill it stops. The speed of the ball on the way up decreases at a uniform acceleration. At the very top of the ball's motion, the speed is 0. At the very bottom of the ball's motion, the acceleration is, if on earth, -9.8m/s squared.
  16. The direction of the ball is strait up, and the speed is constantly deminishing until its velocity is zero. At the top of the balls motion its acceleration is 9.8 m/s squared. Throughout the entire time the ball is in the air it is decelerating at this rate.
  17. As I throw a ball straight up into the air, the direction of the ball's motion is initially upward, although it is actually traveling downward at 9.8 m/s squared. At the very top of a ball's motion, its speed is zero and its acceleration is -9.8 meters per second squared.
  18. Direction: upward Speed: it has an upward velocity from the throw. At the top of the ball's motion (speed): the ball comes to rest. Its speed is 0 m/s. At the top of the ball's motion (acceleration): -9.8 m/s
  19. The direction of the ball is, at first, upwards, then it reaches the top of its path and moves in a downward direction. The speed of the ball becomes less because of the downward pull of gravity. At the top of the ball's motion its speed is 0. At the top of the ball's motion its acceleration is downward at 9.8 m/s.
  20. When you throw a ball up in the air, its direction/velocity on the way up, although it rises up into the air, is actually downward. On its way up, its speed decreases, until it momentarily stops at the very top of the ball’s motion. Its acceleration is -9.8 m/s^2 at the very top.
  21. On its way up the ball actually begins to fall as soon as it leaves your hand. Its weight causes it to accelerate downward and therefore its velocity decreases until it reaches 0 m/s at the top of its motion. Then, it begins to accelerate due to gravity at -9.8 m/s2.
  22. If a ball is thrown straight up into the air, then on its way up the ball will move upward in a straight line and then descend once the velocity of the ball becomes zero. The speed of the ball with decrease on the way up until it hits zero and it will then fall back down. At the very top of the balls motion the speed is zero, but at the same position the acceleration of the ball is -9.8.
  23. The speed of the ball at the very top is 0m/s. On the way up the ball is deccelerating. The direction of the ball changes from up to down as the throw pregresses. The acceleration of any falling object is 9.8 m/s^2, and this is only if there are no other forces present to adjust this falling speed.

Question 3:

Again, consider a situation where we can neglect air resistance. A 1 kg ball is dropped from a height of 30 m above the surface of the earth. The ball is released from rest (ie it is neither thrown up or down, but simply let go). Predict how long it will take for the ball to reach the ground after it is released. Also, compare your answer to the information in Fig. 1.2.2 and see if your result seems reasonable.

Answer:

The ball has traveled a distance of 30 m from its initial position when it strikes the ground. Its initial velocity was zero (released from rest). Plugging this information into eq. (1.2.3), I find that it takes the ball 2.47 seconds to reach the ground. According to Fig. 1.2.2, since it takes 2 seconds for a ball dropped from rest to travel 19.6 m, and it takes 3 seconds for a ball dropped from rest to travel 44.1 m, my result of 2.47 seconds does seem reasonable.
  1. Using the equation x=x0 + v0t + 1/2at2, where initial position is 0, final position is 30m, and initial velocity is 0, solving for t you get about 2.5 s, which does seem reasonable looking at the diagram given in Fig.1.2.2.
  2. It would take 2.47 seconds to reach the ground.
  3. About 2.5 seconds. This seems reasonable with the diagram.
  4. The ball will take about 2.5 seconds to reach the ground after it is released. This seems reasonable.
  5. 2.47s. Yes, because the marble took 3s to fall 44.1m and 2s to fall 19.6m and 2.47s is in between those two.
  6. it should take 2.47 seconds for the ball to reach the ground. this seems reasonable, as 1.2.2 states that after 2 seconds the ball has fallen 19.6m and has a downward velocity of 19.6m/s
  7. about 1.2 sec.
  8. It should take the ball about 2.5 seconds to reach the ground after it is released. This seems reasonable when looking at Fig. 1.2.2, because it took the marble 2 seconds to fall 19.6 m, and 3 seconds to fall 44.1 m. However, I'm not how the difference in mass between a marble and a 1 kg ball would affect the situation.
  9. About 2.5 seconds. This answer also seems reasonable using Fig. 1.2.2
  10. It will take about 2.47 sec. This makes sense with the diagram because at 2 seconds the ball has fallen about 20 m, and at 3 seconds, the ball has fallen about 45 m.
  11. 2.47 seconds
  12. i'm having a little trouble understanding the relation between time and acceleration.
  13. It should take about 2 and a half seconds.
  14. It will take the ball about 2.5 seconds to reach the ground after it is released. This seems reasonable according to the information in Fig. 1.2.2 which shows a ball dropping 44.1 m in 3 seconds, so a drop of 30 m in 2.5 seconds seems reasonable.
  15. present position = initial position + initial velocity x time + .5 x acceleration x time^2 30=0+0xt+.5(9.8)t^2 t=2.47 seconds
  16. After plugging in the numbers to equation 1.2.3, i found that it would land in 2.47 seconds . After comparing it to figure 1.2.2 i think it is a very reasonable answer.
  17. Since the ball is falling 30 meters at a downward velocity of 9.8 meters per second, it seems that it would take the ball about 2.47 seconds to reach the ground. (position formula). This calculation seems reasonable, as at two and three seconds, the position of the ball is 19.6 and 44.1 meters, respectively.
  18. The will take about 1.75 seconds to reach the ground after it is released. This makes sense in relation to figure 1.2.2 because at 30m, the marble was between 2 and 3 seconds. The ball is much heavier than a marble, so it will fall faster.
  19. It will take 2.47 seconds.
  20. It will take about 2.47 seconds for the ball to hit the ground.
  21. It will take approximately 2.47 seconds for the ball to reach the ground.
  22. 2.5 seconds
  23. it will take 3.5 seconds for the ball to hit the ground after it is released.

Question 4:

Look at Fig. 1.2.2, Fig. 1.2.3, and Fig. 1.2.6: Briefly describe/compare/contrast these figures. Please let me know what (if anything) you find confusing about these figures.

Answer:

Your responses below.
  1. In Fig.1.2.2 and 1.2.3 you can see that the acceleration of the ball is constant, the acceleration due to gravity. Looking at these two diagrams, you can see that in the first the ball is accelerating in the direction of its movement, so it covers more distance in each successive second it falls. In the second figure, since the acceleration is opposite the direction of movement, the ball slows down, and therefore covers less distance with each successive second. In Fig. 1.2.6 you see the same pattern in the vertical components of the ball's velocity in that as it rises it slows down and therefore covers less distance each second since its acceleration is in the opposite direction to its movement. As it travels from the peak of its trajectory downward the acceleration is in the same direction as its motion therefore it speeds up and covers more distance in each second. From this diagram you can see that in the horizontal direction the ball does not accelerate, but that component of velocity remains constant, so the ball travels the same horizontal distance each second.
  2. Figure 1.2.2 shows how a ball accelerates toward the earth when it free-falls, figure 1.2.3 shows how a ball still accelerates toward the earth when you throw it up. Figure 1.2.6 shows the same thing when the ball is thrown up at an angle. They are all similar because the acceleration toward the earth due to gravity is constant in all of them, but the initial velocity is different in each figure. In the first figure, the initial velocity is zero, in the second the initial velocity is upward, and in the third the initial velocity is partially upward and partially horizontal. But, despite the differences in initial velocity, the acceleration is the same in each figure.
  3. 1.2.2 and 1.2.3 are the same motion in opposite directions. 1.2.6 shows the trajectory of a thrown object and its force components in the horizontal and vertical directions. I don't find them confusing.
  4. Fig 1.2.2 shows a falling ball, affected only by gravity. The acceleration is constant and the downward speed is picking up. Fig 1.2.3 shows the motion of a ball thrown straight up. It is affected by the throw (which gives the initial upward velocity) and gravity which applies a constant negative acceleration. The ball travels upward for 3 seconds, slowing down because of gravity until it reaches a stop and will begin falling. (This fall is represented in Fig 1.2.2.) Fig 1.2.6 diagrams the motion of a ball thrown upward, at an angle. The distance downfield is represented on the x-axis and the height on the y-axis. The ball's actual (total) velocity at each second is represented by the dark vectors. The lighter arrows represent the horizontal velocity and the vertical velocity because they are independent. The horizontal velocity is constant, while the vertical velocity accelerates due to gravity (as in Fig 1.2.3 and then 1.2.2.)
  5. The two figures are opposites. The first shows a baseball's position, time, velocity and acceleration as it falls and the second shows the same quantities as it is tossed in the air. The pictures are similar in that after one second, the ball descends and ascends the exact same distance. Their velocities reversed because at 0s when the ball is dropped it is still and at 3s when the ball is thrown upward it is still. Basically, the same principles of gravity and relative motion can be observed when a ball is thrown or dropped.
  6. all 3 are similar in that no matter how the ball is thrown or dropped, there is always an acceleration of 9.8m/s downward. Further, 1.2.2 is basically the second half of both figures 1.2.3 and 1.2.6, showing how after the ball has momentarily stopped traveling in the upward direction and is now accelerating downward from a stop. The verticle component of motion and gravity is not affected by horizontal motion.
  7. 1.2.2 is an example of a ball being let go from rest and explaining the time it takes in relation to velocity and distance. 1.2.3 the ball is thrown from rest upward, and the relation of acceleration to velocity. 1.2.6 the ball is thrown from rest at an upward angle and the relation of horizontal and vertical with velocity and acceleration.
  8. In Fig. 1.2.2, an object is dropped from rest. In Fig. 1.2.3, a ball is thrown straight upward. In Fig. 1.2.6, a ball is thrown upward at an angle. Each figure depicts position, velocity, and time. I found Fig. 1.2.6 more confusing than the others. Is the velocity the greatest as the ball is falling downward? It's confusing for me to separate horizontal and vertical velocity.
  9. Fig 1.2.2 shows what happens when a ball is dropped with respect to position, time, velocity, and acceleration. As time elapses the velocity increases while acceleration is constant. Both velocity and acceleration work in the downwards direction. Fig 1.2.3 shows what happens when a ball is thrown straight up in the air. The velocity decreases as time elapses but acceleration is once again constant. Since the ball is being thrown up in the air the direction of the velocity is up but acceleration is still downward just like in the last figure. Fig. 1.2.6 is different because the ball is thrown upward at an angle. Here there are two different components of velocity, the horizontal and vertical components. They are dependent on whether the ball is rising or falling. So if the ball is falling, the vertical component is pointing down. The ball still rises and falls the same as in Figure 1.2.2 and 1.2.3 and the same forces are acting on it except that the final resting place is farther down than the starting place
  10. In each diagram, the ball reaches a vertical height of 44.1 m. In the first, this is because it is being dropped from that height with no initial velocity; in the second and third diagram, the ball reaches that height after being thrown upwards. Each diagram illustrates how there is always a negative acceleration (gravity), and that as the ball falls it's velocity steadily increases. In the second and third diagrams, there is an initial velocity of 29.4 m/s. This velocity causes the ball to rise quickly but slow its ascent as the negative acceleration slows it down until it stops and begins to fall. The third diagram is useful in demonstrating that although there is now a horizontal force, it does not affect the vertical movement of the ball and the vertical forces. This means that the ball will still rise and fall in the same amount of time regardless of its horizontal movement.
  11. Firgure 1.2.2 is describing the position, velocity, acceleration, and time it takes for an object dropped at rest. Figure 1.2.3 shows the difference in position, velocity and acceleration if the object is thrown straight upward instead. The veolcity of an object thrown upward decreases because of the downward acceleration due to gravity. Figure 1.2.6 shows the path of an object if it is thrown upward at an angle. The picture shows that the horizontal velocity is constnat while the vertical velocity deacreases upward and then increases downward. I think these figures make sense.
  12. 1.2.2 focuses on dropping a ball down and how gravity makes it speed up on its way down. 1.2.3 focuses on throwing a ball up and how gravity forces the ball to slow down on its way up. 1.2.6 is showing the height and distance of a ball after it is thrown. It is different from the other two because the ball is moving in two directions, downfield and up or down in the air.
  13. Fig. 1.2.2 describes how to calculate and object's current velocity, which makes up part of figure 1.2.3 which is the formula for calculating and objects present position. Figure 1.2.6 is a representation of an object traveling both vertically and horizontally. The vertical element of the object can be predicted by the formula in figure 1.2.3, while the horizontal element remains constant.
  14. Fig. 1.2.2 gives the position, fall time, velocity and acceleration for a ball dropped from rest, while Fig. 1.2.3 gives these details with respect to a ball thrown straight upward. Fig. 1.2.6 shows a ball thrown neither straight up nor straight down, but rather upward at an angle. This figure also did not include actual numbers for the velocity at each position like the other to figures did. The figures and their descriptions were pretty straightforward and understandable.
  15. Fig. 1.2.2 depicts an object falling and the acceleration and velocity changes taht occure. Figure 1.2.3 shows a ball being first thrown upward, which is the same as it falling accept it is decelerating, and then falling from its highest point, which is the same as figure 1.2.2. Figure 1.2.6 is the same as the first two, however there is an element of horizontal motion added. This horizontal motion has no effect on the vertical movement of the ball, so it will act in the same way as in figure 1.2.3, but now it just moves in another direction as well.
  16. 1.2.2 shows what happens to a falling ball, 1.2.3 shows what happens when a ball is thrown up in the air strait up, and 1.2.6 shows what happens when you throw a ball at an angle. I found figure 1.2.6 slightly confusing about horizontal and vertical directions and how to apply that in equations.
  17. In 1.2.2, a marble is dropped, and the marble's velocity increases by multiples of 9.8 meters/second every second. It is moving downward. In figure 1.2.3, the velocity decreases by multiples of 9.8 meters/second every second until at three seconds, the velocity is zero. Both of these figures travel in a straight line. In figure 1.2.6, gravity acts upon the ball in the same way, except the ball travels in a horizonal flight. The velocity is constant. I am still a bit confused in general about the figures, especially the projectile one.
  18. The first figure is showing what happens to a marble that is dropped from an initial velocity of zero. The second figure shows what happens to a ball that is thrown straight upward. The third figure shows a graph of the second figure. In each figure, the acceleration of the object is always -9.8 m/s/s. I did not find anything confusing about these figures.
  19. In all three figures it takes 3 seconds for the ball to reach 44.1 meters away from its initial position. The first two also have similar velocities and only differ in the being positive or negative.
  20. Figure 1.2.2 shows the position, fall time, velocity, and acceleration of a ball dropped from rest in your hand. Figure 1.2.3 shows the same things, but for a ball thrown straight upward. 1.2.6 gives a diagram of what a ball’s figures are if it is thrown upward, at an angle. The only thing that would have been more helpful is if the book showed an example of how to solve a problem using the equations they supplied.
  21. In figure 1.2.2 the initial velocity of the ball is 0 and then it accelerates downward due to gravity therefore, it has a constantly changing velocity. In figure 1.2.3 the ball starts off with a larger velocity from the force of the throw and as soon as it leaves the person's hand, the ball begins to slowly decelerate until its velocity reaches 0 and then slowly begins to move in the downward direction accelerating again due to gravity. So at the top of the ball's vertical motion when its velocity = 0, this figure becomes the same exact scenario as figure 1.2.2. In figure 1.2.6, the ball is experiencing the same vertical motion as in figure 1.2.3. The only difference is that ball is moving horizontally as well, but this movement is independent of what happens vertically. Also, because gravity only acts in the vertical direction, there is no horizontal acceleration and the horizontal velocity remains constant.
  22. The three figures are simular because they all show the effects of a ball thrown over time, and the contrasts in acceleration, velocity, and position. All three also make the ball go to a height of 44.1m. The first figure shows how a balls velocity increases as it is dropped from a position of rest. The second figure shows what happens to a ball as it is thrown up in the air, and how its velocity decreases. The third figure shows what happens to a ball as it is thrown at an angle.
  23. Fig. 1.2.2 depicts a ball being dropped. Fig. 1.2.3 depicts a ball being thrown upwards. Fig. 1.2.6 depicts a ball being throw foward in an arching direction.

Question 5:

What concepts or equations from the reading did you find confusing? What would you like us to spend class time discussing further?
  • I understood this section well as a result of the physics I've already had in high school.
  • Nothing, thank you!
  • I have seen all of this material before, so there was nothing in the reading that I was confused by.
  • I thought check your understanding #4: Aim High was a very interesting application of this concept. I think I'm okay on the concepts and equations.
  • none
  • I found the reading generally straightfoward, and if we could just go over the motion/gravity equations in class, that would be great.
  • I was a bit confused on question #3:Half a Fall Again on page 18
  • Horizontal and vertical velocity and trajectory motion (please see above).
  • I still dont completely understand what the horizontal and vertical components of velocity actually are and why it is useful to break the total velocity into seperate components.
  • --
  • I think the vector componets are a little confusing. I also don't understand why you have to divide the acceleration by 2 in the position equation.
  • how to answer #3
  • I felt like I understood it all very well.
  • I would like to talk somewhat about the separate components, horizontal and verticle, of velocity in a ball thrown at an angle and also to explain figure 1.2.8.
  • I think that I understand these concepts. I took a physics coarse junior year in high school that covered these concepts thoroughly. Reading this chapter has been a good refresher however.
  • I would like to practice some problems relating to balls thrown at an angle. I thing that doing some examples in class would help solidify everything...and I am a little confused in problem 3 above...do I add a negative sign somewhere?
  • The projectile motion figure confused me. I am also confused abot how an object traveling upward can still have a negative acceleration, as in figure 1.2.3. thanks.
  • I would like to quickly go over all of the equations from this section, just to make sure I thoroughly understand them.
  • I thought the topics presented in the chapter were pretty straightforward.
  • I found the diagrams helpful, because it put numbers into actual pictures, which made it clearer, but I really would have liked it if there were some sample problems using the equations. I think it would be very helpful if we did some problems in class, like question 3 on this reading quiz.
  • I think I pretty much understood everything that was discussed in this section. I mean I know it's true and it's been proven, but I always have a hard time comprehending that something thrown horizontally from the same height and at the same time as something that is just dropped will reach the ground at the same time. I've seen it happen so I know it's true, but for some reason I just think it's kind of odd.
  • I think i understood the equations and concepts pretty well, but it would be useful to go over different problems like in question 3 in order to get some practice.
  • I understand it all basically.