Question 1

If the acceleration of an object is zero,then that object cannot be moving.

Accepted Answer

An object can move at a constant velocity without accelerating, meaning its speed and direction remain unchanged.

Question 2

You drive 6.0 km at 50 km/h and then another 6.0 km at 90 km/h.Your average speed over the 12 km drive will be
A)greater than 70 km/h.
B)equal to 70 km/h.
C)less than 70 km/h.
D)exactly 38 km/h.
E)It cannot be determined from the information given because we must also know directions traveled.

Accepted Answer

To find the average speed, we need to find the total distance traveled and divide it by the total time taken.

Distance traveled = 6 km + 6 km = 12 km
Time taken = (6 km/50 km/h) + (6 km/90 km/h) = 0.12 h + 0.067 h = 0.187 h

Average speed = distance/time = 12 km/0.187 h = 64.17 km/h

Therefore, the average speed over the 12 km drive will be less than 70 km/h (Option C).

Question 3

If the velocity of an object is zero at one instant,what is true about the acceleration of that object? (There could be more than one correct choice.)
A)The acceleration could be positive.
B)The acceleration could be negative.
C)The acceleration could be zero.
D)The acceleration must be zero.

Accepted Answer

An object can have zero velocity at a particular instant while accelerating, meaning its acceleration could be positive, negative, or zero. Zero velocity does not imply zero acceleration; it could be changing direction or starting to move.

Question 4

Which of the following quantities has units of a displacement? (There could be more than one correct choice.) A)32 ft/s² vertically downward B)40 km southwest C)9.8 m/s² D)-120 m/s E)186,000 mi

Accepted Answer

Displacement is a vector quantity that represents the change in position of an object. It has both magnitude and direction. Choices B (40 km southwest) and E (186,000 mi) specify both magnitude and direction, making them correct representations of displacement.

Question 5

Under what condition is average velocity equal to the average of the object's initial and final velocity?
A)This can only occur if there is no acceleration.
B)The acceleration is constant.
C)This can occur only when the velocity is zero.
D)The acceleration must be constantly increasing.
E)The acceleration must be constantly decreasing.

Accepted Answer

Average velocity is defined as the displacement of an object divided by the time taken for that displacement. When acceleration is constant, the object's displacement can be calculated using the equation: displacement = (final velocity - initial velocity) x time. Thus, the average velocity can be calculated as (final velocity + initial velocity)/2, which is the average of the object's initial and final velocity. Therefore, option B is correct.

Question 6

Suppose that a car traveling to the west begins to slow down as it approaches a traffic light.Which of the following statements about its acceleration is correct?
A)The acceleration is toward the east.
B)Since the car is slowing down, its acceleration must be negative.
C)The acceleration is zero.
D)The acceleration is toward the west.

Accepted Answer

Acceleration is defined as the rate of change of velocity. If a car is slowing down while traveling west, its acceleration is in the opposite direction of its motion, which is toward the east. This is because acceleration is vector and points in the direction of the change in velocity.

Question 7

Which of the following situations is impossible?
A)An object has velocity directed east and acceleration directed west.
B)An object has velocity directed east and acceleration directed east.
C)An object has zero velocity but non-zero acceleration.
D)An object has constant non-zero acceleration and changing velocity.
E)An object has constant non-zero velocity and changing acceleration.

Accepted Answer

An object cannot have a constant non-zero velocity if its acceleration is changing. Acceleration is the rate of change of velocity, so if acceleration changes, velocity must also change.

Question 8

When is the average velocity of an object equal to the instantaneous velocity?
A)only when the velocity is increasing at a constant rate
B)only when the velocity is decreasing at a constant rate
C)when the velocity is constant
D)always
E)never

Accepted Answer

When the velocity is constant, the average velocity over any time interval is equal to the instantaneous velocity at any point within that interval.

Question 9

If the velocity of an object is zero at some point,then its acceleration must also be zero at that point.

Accepted Answer

An object can have zero velocity at a point but still be accelerating. For example, when a ball thrown upwards reaches its highest point, its velocity is zero, but it has a downward acceleration due to gravity.

Question 10

When a ball is thrown straight up with no air resistance,the acceleration at its highest point
A)is upward
B)is downward
C)is zero
D)reverses from upward to downward
E)reverses from downward to upward

Accepted Answer

The acceleration due to gravity is always directed downward, regardless of the object's motion. At the highest point, the velocity of the ball is zero, but the acceleration remains directed downward at approximately 9.8 m/s^2.

Question 11

A racing car accelerates uniformly from rest along a straight track.This track has markers spaced at equal distances along it from the start,as shown in the figure.The car reaches a speed of 140 km/h as it passes marker 2.  Where on the track was the car when it was traveling at half this speed,that is at 70 km/h?
A)Before marker 1
B)At marker 1
C)Between marker 1 and marker 2

Accepted Answer

The answer of A racing car accelerates uniformly from rest...

Question 12

Consider a car that travels between points A and B.The car's average speed can be greater than the magnitude of its average velocity,but the magnitude of its average velocity can never be greater than its average speed.

Accepted Answer

Average speed is calculated as the total distance traveled divided by the total time taken, while average velocity is the displacement (straight-line distance between the starting and ending points) divided by the total time taken. Since the path traveled (distance) can be longer than the displacement, average speed can be greater than the magnitude of average velocity, but the reverse cannot happen because displacement cannot be greater than the path length.

Question 13

Suppose that a car traveling to the east (+x direction)begins to slow down as it approaches a traffic light.Which statement concerning its acceleration must be correct?
A)Its acceleration is in the +x direction.
B)Its acceleration is in the -x direction.
C)Its acceleration is zero.
D)Its acceleration is decreasing in magnitude as the car slows down.

Accepted Answer

The car is slowing down, which means its velocity is decreasing. The acceleration is in the direction of the change in velocity, so the acceleration must be in the opposite direction of the car's motion, which is the -x direction.

Question 14

A rock from a volcanic eruption is launched straight up.Which one of the following statements about this rock while it is in the air is correct if you neglect the presence of air?
A)On the way up, its acceleration is downward and its velocity is upward, and at the highest point both its velocity and acceleration are zero.
B)On the way down, both its velocity and acceleration are downward, and at the highest point both its velocity and acceleration are zero.
C)Throughout the motion, the acceleration is downward, and the velocity is always in the same direction as the acceleration.
D)The acceleration is downward at all points in the motion.
E)The acceleration is downward at all points in the motion except that is zero at the highest point.

Accepted Answer

The acceleration due to gravity is always downward throughout the motion of the rock, regardless of whether the rock is moving up, at its highest point, or moving down.

Question 15

Suppose that an object is moving with a constant velocity.Which statement concerning its acceleration must be correct?
A)The acceleration is constantly increasing.
B)The acceleration is constantly decreasing.
C)The acceleration is a constant non-zero value.
D)The acceleration is equal to zero.

Accepted Answer

If an object is moving with a constant velocity, then its acceleration is zero. This is because acceleration is defined as the rate of change of velocity, and if the velocity is not changing, then the rate of change is zero. Therefore, choice D is correct. Choices A, B, and C are incorrect.

Question 16

Suppose that a car traveling to the west (-x direction)begins to slow down as it approaches a traffic light.Which statement concerning its acceleration must be correct?
A)Its acceleration is positive.
B)Its acceleration is negative.
C)Its acceleration is zero.
D)Its acceleration is decreasing in magnitude as the car slows down.

Accepted Answer

Since the car is slowing down in the -x direction (to the west), its acceleration is in the opposite direction (east or +x direction) to decelerate, making the acceleration positive.

Question 17

An object moving i n the +x direction has an acceleration of +2.0 m/s².This means the object A)travels 2.0 m in every second. B)is traveling at 2.0 m/s. C)is decreasing its velocity by 2.0 m/s every second. D)is increasing its velocity by 2.0 m/s every second.

Accepted Answer

An acceleration of +2.0 m/s^2 in the +x direction means that the velocity of the object is increasing by 2.0 m/s every second. So, the correct choice is D. Choice A is incorrect because it implies a constant velocity, whereas the question mentions an acceleration. Choice B is incorrect because it only gives the current velocity, not the change in velocity. Choice C is incorrect because it implies a negative acceleration, whereas the question mentions a positive acceleration.

Question 18

An auto manufacturer advertises that their car can go "from zero to sixty in eight seconds." This is a description of what characteristic of the car's motion?
A)average speed
B)instantaneous speed
C)average acceleration
D)instantaneous acceleration
E)displacement

Accepted Answer

The time it takes for the car to go from zero to sixty is a measure of its average acceleration. This is because acceleration is defined as the change in velocity over time, and going from zero velocity to a velocity of sixty miles per hour in eight seconds represents an acceleration. The other options (average speed, instantaneous speed, instantaneous acceleration, and displacement) do not adequately describe this characteristic of the car's motion.

Question 19

If the velocity of an object is zero,then that object cannot be accelerating.

Accepted Answer

An object can have zero velocity at a certain instant while still accelerating. For example, when an object thrown upwards reaches its highest point, its velocity is zero, but it is still accelerating due to gravity.

Question 20

Which of the following quantities has units of a velocity? (There could be more than one correct choice.) A)40 km southwest B)-120 m/s C)9.8 m/s² downward D)186,000 mi E)9.8 m/s downward

Accepted Answer

B) -120 m/s has units of velocity, where the negative sign indicates direction.
E) 9.8 m/s downward also has units of velocity, with the direction specified. The other choices do not have units of velocity. A) is a distance in a specific direction, D) is a distance with no direction specified, and C) is an acceleration with direction specified.

Quiz 2: Kinematics: Motion in One Dimension

If the acceleration of an object is zero,then that object cannot be moving.

You drive 6.0 km at 50 km/h and then another 6.0 km at 90 km/h.Your average speed over the 12 km drive will be

If the velocity of an object is zero at one instant,what is true about the acceleration of that object? (There could be more than one correct choice.)

Which of the following quantities has units of a displacement? (There could be more than one correct choice.)

Under what condition is average velocity equal to the average of the object's initial and final velocity?

Suppose that a car traveling to the west begins to slow down as it approaches a traffic light.Which of the following statements about its acceleration is correct?

Which of the following situations is impossible?

When is the average velocity of an object equal to the instantaneous velocity?

If the velocity of an object is zero at some point,then its acceleration must also be zero at that point.

When a ball is thrown straight up with no air resistance,the acceleration at its highest point

Consider a car that travels between points A and B.The car's average speed can be greater than the magnitude of its average velocity,but the magnitude of its average velocity can never be greater than its average speed.

Suppose that a car traveling to the east (+x direction) begins to slow down as it approaches a traffic light.Which statement concerning its acceleration must be correct?

A rock from a volcanic eruption is launched straight up.Which one of the following statements about this rock while it is in the air is correct if you neglect the presence of air?

Suppose that an object is moving with a constant velocity.Which statement concerning its acceleration must be correct?

Suppose that a car traveling to the west (-x direction) begins to slow down as it approaches a traffic light.Which statement concerning its acceleration must be correct?

An object moving i n the +x direction has an acceleration of +2.0 m/s².This means the object

An auto manufacturer advertises that their car can go "from zero to sixty in eight seconds." This is a description of what characteristic of the car's motion?

If the velocity of an object is zero,then that object cannot be accelerating.

Which of the following quantities has units of a velocity? (There could be more than one correct choice.)

Quiz 2: Kinematics: Motion in One Dimension

If the acceleration of an object is zero,then that object cannot be moving.

You drive 6.0 km at 50 km/h and then another 6.0 km at 90 km/h.Your average speed over the 12 km drive will be

If the velocity of an object is zero at one instant,what is true about the acceleration of that object? (There could be more than one correct choice.)

Which of the following quantities has units of a displacement? (There could be more than one correct choice.)

Under what condition is average velocity equal to the average of the object's initial and final velocity?

Suppose that a car traveling to the west begins to slow down as it approaches a traffic light.Which of the following statements about its acceleration is correct?

Which of the following situations is impossible?

When is the average velocity of an object equal to the instantaneous velocity?

If the velocity of an object is zero at some point,then its acceleration must also be zero at that point.

When a ball is thrown straight up with no air resistance,the acceleration at its highest point

Consider a car that travels between points A and B.The car's average speed can be greater than the magnitude of its average velocity,but the magnitude of its average velocity can never be greater than its average speed.

Suppose that a car traveling to the east (+x direction) begins to slow down as it approaches a traffic light.Which statement concerning its acceleration must be correct?

A rock from a volcanic eruption is launched straight up.Which one of the following statements about this rock while it is in the air is correct if you neglect the presence of air?

Suppose that an object is moving with a constant velocity.Which statement concerning its acceleration must be correct?

Suppose that a car traveling to the west (-x direction) begins to slow down as it approaches a traffic light.Which statement concerning its acceleration must be correct?

An object moving i n the +x direction has an acceleration of +2.0 m/s2.This means the object

An auto manufacturer advertises that their car can go "from zero to sixty in eight seconds." This is a description of what characteristic of the car's motion?

If the velocity of an object is zero,then that object cannot be accelerating.

Which of the following quantities has units of a velocity? (There could be more than one correct choice.)

An object moving i n the +x direction has an acceleration of +2.0 m/s².This means the object