Question 1

A ball is thrown downward in the absence of air.After it has been released,which statement(s)concerning its acceleration is correct? (There could be more than one correct choice.)
A)Its acceleration is constantly increasing.
B)Its acceleration is constant.
C)Its acceleration is constantly decreasing.
D)Its acceleration is zero.
E)Its acceleration is greater than g.

Accepted Answer

In the absence of air, the only force acting on the ball is gravity. Since the gravitational force on the ball is constant, its acceleration is also constant and equal to g, which is approximately 9.8 m/s^2. Therefore, statement B is correct, while statements A, C, D, and E are incorrect.

Question 2

If the position versus time graph of an object is a horizontal line,the object is
A)moving with constant non-zero speed.
B)moving with constant non-zero acceleration.
C)at rest.
D)moving with increasing speed.

Accepted Answer

A horizontal line on a position versus time graph indicates that the position of the object does not change as time progresses. This means the object is not moving, hence it is at rest.

Question 3

An object is moving with constant non-zero velocity in the +x direction.The position versus time graph of this object is
A)a horizontal straight line.
B)a vertical straight line.
C)a straight line making an angle with the time axis.
D)a parabolic curve.

Accepted Answer

A constant non-zero velocity means the object's position changes linearly with time, resulting in a straight line with a slope (angle) on a position vs. time graph.

Question 4

A ball is thrown straight up,reaches a maximum height,then falls to its initial height.Which of the following statements about the direction of the velocity and acceleration of the ball as it is going up is correct?
A)Both its velocity and its acceleration point upward.
B)Its velocity points upward and its acceleration points downward.
C)Its velocity points downward and its acceleration points upward.
D)Both its velocity and its acceleration points downward.

Accepted Answer

When the ball is going up, it is decelerating due to the force of gravity, which is pulling it down. Thus, the acceleration is downward. However, the ball's initial velocity is upward, so the velocity and acceleration are in opposite directions. Therefore, choice B is correct.

Question 5

From the edge of a roof top you toss a green ball upwards with initial speed v₀ and a blue ball downwards with the same initial speed.Neglect air.When they reach the ground below A)the green ball will be moving faster than the blue ball. B)the blue ball will be moving faster than the green ball. C)the two balls will have the same speed.

Accepted Answer

The green ball and blue ball have the same initial speed. Neglecting air resistance means that there is no external force acting on the balls once they are released, except for the force of gravity. Because the balls have the same initial velocity, they will experience the same acceleration due to gravity. Therefore, they will both reach the ground with the same speed. It doesn't matter whether one is moving upwards and the other downwards - they are still affected by the same gravitational force.

Question 6

The slope of a velocity versus time graph gives
A)the distance traveled.
B)velocity.
C)acceleration.
D)displacement.

Accepted Answer

The slope of a velocity versus time graph represents the rate of change of velocity, which is acceleration. Therefore, the correct choice is C.

Question 7

The slope of a position versus time graph gives
A)the distance traveled.
B)velocity.
C)acceleration.
D)displacement.

Accepted Answer

The slope of a position versus time graph represents the rate of change of position with respect to time, which is velocity. Therefore, the correct answer is B.

Question 8

Suppose a ball is thrown straight up and there is no air.What is its acceleration just before it reaches its highest point?
A)zero
B)slightly less than g
C)exactly g
D)slightly greater than g

Accepted Answer

The acceleration of the ball is exactly g (9.8 m/s^2 downward) throughout its flight, including just before it reaches its highest point, due to gravity.

Question 9

An object is moving with constant non-zero velocity in the +x direction.The velocity versus time graph of this object is
A)a horizontal straight line.
B)a vertical straight line.
C)a straight line making an angle with the time axis.
D)a parabolic curve.

Accepted Answer

Since the object is moving with constant non-zero velocity in the +x direction, its velocity does not change with time. Therefore, the velocity versus time graph will be a horizontal straight line.

Question 10

An object is moving with constant non-zero acceleration in the +x direction.The velocity versus time graph of this object is
A)a horizontal straight line.
B)a vertical straight line.
C)a straight line making an angle with the time axis.
D)a parabolic curve.

Accepted Answer

A constant non-zero acceleration implies a constant rate of change of velocity with time, which is represented by a straight line making an angle with the time axis on a velocity versus time graph.

Question 11

Two objects are dropped from a bridge,an interval of 1.0 s apart.Neglect air.During the time that both objects continue to fall,their separation
A)increases.
B)decreases.
C)stays constant.
D)increases at first, but then stays constant.
E)decreases at first, but then stays constant.

Accepted Answer

The separation between the two objects increases because both objects are accelerating due to gravity at the same rate, but the second object starts its fall 1.0 s later, so the first object always has a head start, making the distance between them grow over time.

Question 12

If the velocity versus time graph of an object is a straight line making an angle of +30° (counter clockwise)with the time axis,the object is
A)moving with constant non-zero speed.
B)moving with constant non-zero acceleration.
C)at rest.
D)moving with increasing acceleration.

Accepted Answer

When the velocity-time graph of an object is a straight line making an angle with the time axis, it indicates that the object has a constant slope on this graph. The slope of a velocity-time graph represents acceleration. Therefore, if the line is straight and not horizontal, the object is moving with a constant non-zero acceleration.

Question 13

If the velocity versus time graph of an object is a horizontal line,the object is
A)moving with zero acceleration.
B)moving with constant non-zero acceleration.
C)at rest.
D)moving with increasing speed.

Accepted Answer

A horizontal line on a velocity versus time graph means that the velocity of the object is not changing over time, meaning there is no acceleration (since acceleration is the rate of change of velocity). Therefore, the object is moving with zero acceleration.

Question 14

A 10-kg rock and 20-kg rock are dropped from the same height and there is no air.If it takes the 20-kg rock a time T to reach the ground,what time will it take the 10-kg rock to reach the ground?
A)4T
B)2T
C)T
D)T/2
E)T/4

Accepted Answer

The time it takes for an object to fall to the ground does not depend on its mass, only on the height it is dropped from and the acceleration due to gravity. Therefore, both rocks will take the same amount of time to reach the ground, which is T.

Question 15

Two objects are thrown from the top of a tall building.One is thrown up,and the other is thrown down,both with the same initial speed.What are their speeds when they hit the street? Neglect air.
A)The one thrown up is traveling faster.
B)The one thrown down is traveling faster.
C)They are traveling at the same speed.
D)It is impossible to tell because the height of the building is not given.

Accepted Answer

Both objects will hit the street with the same velocity because they were given the same initial speed and both are subjected to the same acceleration due to gravity. The direction of their motion does not affect their speed when they hit the ground.

Question 16

An object is moving with constant non-zero acceleration in the +x direction.The position versus time graph of this object is
A)a horizontal straight line.
B)a vertical straight line.
C)a straight line making an angle with the time axis.
D)a parabolic curve.

Accepted Answer

If an object is moving with constant non-zero acceleration in the +x direction, then the position versus time graph of this object should be a parabolic curve. This is because the acceleration is changing the velocity of the object, which in turn changes its position, resulting in a curve rather than a straight line.

Question 17

A 10-kg rock and a 20-kg rock are dropped at the same time and there is no air.If the 10-kg rock falls with acceleration a,what is the acceleration of the 20-kg rock?
A)4a
B)2a
C)a
D)a/2
E)a/4

Accepted Answer

The acceleration of an object due to gravity (neglecting air resistance) is constant and independent of the object's mass. Therefore, both rocks will experience the same acceleration which is equal to "a". Hence, the correct choice is (C) "a".

Question 18

A 10-kg rock and a 20-kg rock are thrown upward with the same initial speed v₀ and there is no air.If the 10-kg rock reaches a maximum height h,what maximum height will the 20-kg ball reach? A)h/4 B)h/2 C)h D)2h E)4h

Accepted Answer

The maximum height of an object in projectile motion only depends on its initial speed and the force of gravity acting upon it, not its mass. Therefore, both rocks will reach the same maximum height h.

Question 19

Ball A is dropped from the top of a building.One second later,ball B is dropped from the same building.Neglect air.As time progresses,the difference in their speeds
A)increases.
B)remains constant.
C)decreases.
D)cannot be determined from the information given.

Accepted Answer

Both balls are in free fall and thus accelerate at the same rate due to gravity. The speed difference established in the first second (when only ball A is moving) remains constant over time.

Question 20

Brick A is dropped from the top of a building.Brick B is thrown straight down from the same building.Neglect air.Which statement about their accelerations is correct?
A)The acceleration of A is greater than the acceleration of B.
B)The acceleration of B is greater than the acceleration of A.
C)The two bricks have exactly the same acceleration.
D)Neither brick has any acceleration once it is released.

Accepted Answer

Both bricks will experience the same constant acceleration due to gravity, regardless of their initial velocities or how they were released. Therefore, they will have exactly the same acceleration.

Quiz 2: Kinematics: Motion in One Dimension

A ball is thrown downward in the absence of air.After it has been released,which statement(s) concerning its acceleration is correct? (There could be more than one correct choice.)

If the position versus time graph of an object is a horizontal line,the object is

An object is moving with constant non-zero velocity in the +x direction.The position versus time graph of this object is

A ball is thrown straight up,reaches a maximum height,then falls to its initial height.Which of the following statements about the direction of the velocity and acceleration of the ball as it is going up is correct?

From the edge of a roof top you toss a green ball upwards with initial speed v₀ and a blue ball downwards with the same initial speed.Neglect air.When they reach the ground below

The slope of a velocity versus time graph gives

The slope of a position versus time graph gives

Suppose a ball is thrown straight up and there is no air.What is its acceleration just before it reaches its highest point?

An object is moving with constant non-zero velocity in the +x direction.The velocity versus time graph of this object is

An object is moving with constant non-zero acceleration in the +x direction.The velocity versus time graph of this object is

Two objects are dropped from a bridge,an interval of 1.0 s apart.Neglect air.During the time that both objects continue to fall,their separation

If the velocity versus time graph of an object is a straight line making an angle of +30° (counter clockwise) with the time axis,the object is

If the velocity versus time graph of an object is a horizontal line,the object is

A 10-kg rock and 20-kg rock are dropped from the same height and there is no air.If it takes the 20-kg rock a time T to reach the ground,what time will it take the 10-kg rock to reach the ground?

Two objects are thrown from the top of a tall building.One is thrown up,and the other is thrown down,both with the same initial speed.What are their speeds when they hit the street? Neglect air.

An object is moving with constant non-zero acceleration in the +x direction.The position versus time graph of this object is

A 10-kg rock and a 20-kg rock are dropped at the same time and there is no air.If the 10-kg rock falls with acceleration a,what is the acceleration of the 20-kg rock?

A 10-kg rock and a 20-kg rock are thrown upward with the same initial speed v₀ and there is no air.If the 10-kg rock reaches a maximum height h,what maximum height will the 20-kg ball reach?

Ball A is dropped from the top of a building.One second later,ball B is dropped from the same building.Neglect air.As time progresses,the difference in their speeds

Brick A is dropped from the top of a building.Brick B is thrown straight down from the same building.Neglect air.Which statement about their accelerations is correct?