Question 1

Jogging Jake runs at 4 m/s along a train flatcar that moves at 10 m/s in the same direction. Jake's speed relative to the ground is
A)6 m/s.
B)10 m/s.
C)14 m/s.
D)none of the above

Accepted Answer

Jake's speed relative to the ground is the sum of his speed relative to the train and the train's speed relative to the ground, which is 4 m/s + 10 m/s = 14 m/s.

Question 2

A rock dropped from a 5-m height accelerates at 10 m/s² and strikes the ground 1 s later. If the rock is dropped from a height of 2.5 m, its acceleration of fall is A)half. B)the same. C)twice. D)four times as much.

Accepted Answer

The acceleration due to gravity is constant and does not depend on the starting height of the object. Therefore, the acceleration of the rock when dropped from a height of 2.5 m will be the same as when dropped from 5 m, which is 10 m/s^2.

Question 3

When you walk at an average speed of 4 m/s, in 5 s you'll cover a distance of
A)2 m.
B)10 m.
C)15 m.
D)20 m.

Accepted Answer

To find the distance covered in 5 seconds we can use the formula:
Distance = Speed x Time
Plugging in the given values, we get:
Distance = 4 m/s x 5 s = 20 meters
Therefore, the distance covered in 5 seconds at an average speed of 4 m/s is 20 meters, which is option D.

Question 4

If a car increases its velocity from zero to 60 m/s in 10 seconds, its acceleration is A)3 m/s². B)6 m/s². C)60 m/s². D)600 m/s².

Accepted Answer

Acceleration = (final velocity - initial velocity) / time taken 
Here, final velocity = 60 m/s, initial velocity = 0, time taken = 10 seconds

Therefore, acceleration = (60 - 0) / 10 = 6 m/s^2.

So, the correct option is B, which is 6 m/s^2.

Question 5

The two measurements necessary for calculating average speed are
A)acceleration and time.
B)velocity and time.
C)distance and time.
D)distance and acceleration.
E)velocity and distance.

Accepted Answer

Average speed is calculated by dividing the total distance traveled by an object by the total time taken, so the two measurements required are distance and time. Choice C mentions these two measurements, making it the correct answer.

Question 6

While a car travels around a circular track at a constant speed, its
A)acceleration is zero.
B)velocity is zero.
C)inertia is zero.
D)none of the above

Accepted Answer

When a car travels around a circular track at a constant speed, its direction changes continuously, which means its velocity is changing (since velocity is a vector quantity that includes both speed and direction). This change in velocity indicates the presence of acceleration (centripetal acceleration, in this case), directed towards the center of the circular path. Therefore, options A, B, and C are incorrect, making D the correct choice.

Question 7

A cart maintains a constant velocity of 100 m/s for 10 seconds. During this interval its acceleration is A)zero. B)1 m/s². C)10 m/s². D)none of the above

Accepted Answer

Since the cart maintains a constant velocity of 100 m/s for 10 seconds, there is no change in its velocity and hence no acceleration. Thus, option A is the correct choice.

Question 8

You're at rest in a hammock when a hungry mosquito sees an opportunity for lunch. A mild 2-m/s breeze is blowing. If the mosquito joins you for lunch it should hover over you by flying
A)against the breeze at 2 m/s.
B)with the breeze at 2 m/s.
C)a bit faster than wind speed.
D)none of the above

Accepted Answer

To hover over a stationary target while there's a breeze, the mosquito must fly against the breeze at a speed equal to the wind speed to remain stationary relative to the ground.

Question 9

The speedometer of an automobile reads
A)average speed.
B)instantaneous speed.
C)accelerated speed.

Accepted Answer

The speedometer of an automobile shows the instantaneous speed or the current speed of the vehicle at that particular moment. It does not show the average speed or the accelerated speed.

Question 10

Katelyn runs along the aisle of a train that moves at 8 m/s. Her speed relative to the floor is 3 m/s. Her speed relative to an observer at rest on the ground is
A)5 m/s.
B)11 m/s.
C)either depending on her running direction
D)none of the above

Accepted Answer

Katelyn's speed relative to an observer on the ground depends on her running direction. If she runs in the same direction as the train, her speed relative to the ground is 11 m/s (8 m/s + 3 m/s). If she runs in the opposite direction, her speed relative to the ground is 5 m/s (8 m/s - 3 m/s).

Question 11

A ball rolls along a horizontal track in a certain time. If the track has a dip in it, the time to roll the length of the track will be
A)less.
B)the same.
C)more.

Accepted Answer

When a ball rolls along a track with a dip, it gains speed due to the gravitational potential energy converting into kinetic energy as it goes down the dip and loses less time going up because of the gained speed, thus completing the track in less time overall compared to a flat track.

Question 12

Jogging Jake runs at 4 m/s along a train flatcar that moves at 10 m/s in the opposite direction. Jake's speed relative to the ground is
A)6 m/s.
B)10 m/s.
C)14 m/s.
D)none of the above

Accepted Answer

To find Jake's speed relative to the ground we need to add his velocity to the velocity of the train flatcar. Since the train and Jake are moving in opposite directions, we subtract the velocity of the train from Jake's velocity. This gives us:

Jake's velocity relative to the ground = Jake's velocity – train's velocity
= 4 m/s - (-10 m/s)
= 4 m/s + 10 m/s
= 14 m/s

Therefore, the answer is (A) 6 m/s.

Question 13

If an object moves with constant acceleration, its velocity must
A)be constant also.
B)change by the same amount each second.
C)change by varying amounts depending on its speed.
D)always decrease.

Accepted Answer

If an object moves with constant acceleration, its velocity must change by the same amount each second. This is because acceleration is defined as the rate at which velocity changes. Therefore, if acceleration is constant, velocity will change by the same amount each second.

Question 14

A ball rolls along a horizontal track in a certain time. If the track has a small upward dent in it, the time to roll the length of the track will be
A)less.
B)the same.
C)more.

Accepted Answer

When the ball encounters a small upward dent or bump, it experiences a change in its motion due to the presence of gravitational potential energy. As a result, it slows down, and it will take more time to cover the same distance than on a flat track. Therefore, the time to roll the length of the track will be more.

Question 15

A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the opposite direction has a speed of
A)0 m/s.
B)3 m/s.
C)4 m/s.
D)6 m/s.

Accepted Answer

When a mosquito flies at 3 m/s against a breeze blowing at 3 m/s in the opposite direction, their speeds cancel each other out, resulting in a net speed of 0 m/s.

Question 16

A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the same direction has a speed of
A)0 m/s.
B)3 m/s.
C)4 m/s.
D)6 m/s.

Accepted Answer

The mosquito's speed and the breeze's speed are in the same direction, so they add up: 3 m/s + 3 m/s = 6 m/s.

Question 17

A vehicle undergoes acceleration when it
A)gains speed.
B)loses speed.
C)changes its direction.
D)all of the above

Accepted Answer

Acceleration is defined as a change in velocity, which can occur through a change in speed (either gaining or losing speed) or a change in direction.

Question 18

The average speed of a horse that gallops 10 kilometers in 30 minutes is
A)15 km/h.
B)20 km/h.
C)30 km/h.
D)40 km/h.

Accepted Answer

The average speed of the horse is calculated as:
Average Speed = Total Distance / Total Time
Here, the horse gallops 10 km in 30 minutes, which is half an hour.
Therefore, Average Speed = 10 km / 0.5 hours = 20 km/h. 
Hence, the best choice would be B, which is 20 km/h.

Question 19

A cart changes its speed from 90 m/s to 100 m/s in 10 seconds. During this interval its acceleration is A)zero. B)1 m/s². C)10 m/s². D)none of the above

Accepted Answer

Acceleration is defined as the change in velocity over time. Here, the change in velocity is $100 \, \text{m/s} - 90 \, \text{m/s} = 10 \, \text{m/s}$, and the time taken for this change is 10 seconds. Therefore, acceleration = $ \frac{10 \, \text{m/s}}{10 \, \text{s}} = 1 \, \text{m/s}^2$.

Question 20

An object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second, and 8 meters again during the third second. Its acceleration is A)0 m/s². B)5 m/s². C)8 m/s². D)24 m/s².

Accepted Answer

Acceleration is the rate of change of velocity with time. Since the object in the question covers a distance of 8 meters in each second, its velocity at the end of each second is 8 m/s. However, we cannot determine the acceleration based on the distance covered alone. We need to know the time taken and the initial velocity as well. Since these values are not given in the question, we cannot determine the acceleration accurately. Therefore, the best choice is A, 0 m/s^2, which indicates that we do not have enough information to determine the acceleration.

Quiz 3: Linear Motion

Jogging Jake runs at 4 m/s along a train flatcar that moves at 10 m/s in the same direction. Jake's speed relative to the ground is

A rock dropped from a 5-m height accelerates at 10 m/s2 and strikes the ground 1 s later. If the rock is dropped from a height of 2.5 m, its acceleration of fall is

When you walk at an average speed of 4 m/s, in 5 s you'll cover a distance of

If a car increases its velocity from zero to 60 m/s in 10 seconds, its acceleration is

The two measurements necessary for calculating average speed are

While a car travels around a circular track at a constant speed, its

A cart maintains a constant velocity of 100 m/s for 10 seconds. During this interval its acceleration is

You're at rest in a hammock when a hungry mosquito sees an opportunity for lunch. A mild 2-m/s breeze is blowing. If the mosquito joins you for lunch it should hover over you by flying

The speedometer of an automobile reads

Katelyn runs along the aisle of a train that moves at 8 m/s. Her speed relative to the floor is 3 m/s. Her speed relative to an observer at rest on the ground is

A ball rolls along a horizontal track in a certain time. If the track has a dip in it, the time to roll the length of the track will be

Jogging Jake runs at 4 m/s along a train flatcar that moves at 10 m/s in the opposite direction. Jake's speed relative to the ground is

If an object moves with constant acceleration, its velocity must

A ball rolls along a horizontal track in a certain time. If the track has a small upward dent in it, the time to roll the length of the track will be

A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the opposite direction has a speed of

A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the same direction has a speed of

A vehicle undergoes acceleration when it

The average speed of a horse that gallops 10 kilometers in 30 minutes is

A cart changes its speed from 90 m/s to 100 m/s in 10 seconds. During this interval its acceleration is

An object covers a distance of 8 meters in the first second of travel, another 8 meters during the next second, and 8 meters again during the third second. Its acceleration is

A rock dropped from a 5-m height accelerates at 10 m/s² and strikes the ground 1 s later. If the rock is dropped from a height of 2.5 m, its acceleration of fall is