Physics Motion Online Quiz

1. A train approaches a small town with a constant velocity of +28.6 m/s. The operator applies the brake, reducing the train's velocity to +11.4 m/s. If the average acceleration of the train during braking is –1.35 m/s2, for what elapsed time does the operator apply the brake?

8.44 s

12.74s

3.38 s

5.92 s

10.4 s

We can use the formula:

[v_f = v_i + at]

Where:

- (v_f) is the final velocity (11.4 m/s).

- (v_i) is the initial velocity (28.6 m/s).

- (a) is the acceleration (-1.35 m/s²).

- (t) is the time.

Now, plug in the values:

[11.4 = 28.6 + (-1.35)t]

Now, solve for (t):

[-1.35t = 11.4 - 28.6]

[-1.35t = -17.2]

[t = {-17.2}/{-1.35} = (approx) 12.74]

So, the operator applies the brake for approximately 12.74 seconds.

Explanation

We can use the formula:

[v_f = v_i + at]

Where:

- (v_f) is the final velocity (11.4 m/s).

- (v_i) is the initial velocity (28.6 m/s).

- (a) is the acceleration (-1.35 m/s²).

- (t) is the time.

Now, plug in the values:

[11.4 = 28.6 + (-1.35)t]

Now, solve for (t):

[-1.35t = 11.4 - 28.6]

[-1.35t = -17.2]

[t = {-17.2}/{-1.35} = (approx) 12.74]

So, the operator applies the brake for approximately 12.74 seconds.

2. Starting from rest, a particle confined to move along a straight line is accelerated at a rate of 5.0 m/s2.

The particle travels 5.0 m during each second.

The particle travels 5.0 m only during the first second.

The speed of the particle increases by 5.0 m/s during each second.

The acceleration of the particle increases by 5.0 m/s2 during each second.

The final speed of the particle will be proportional to the distance that the particle covers.

The correct answer is "The speed of the particle increases by 5.0 m/s during each second." This answer is supported by the statement that the particle is accelerated at a rate of 5.0 m/s2. Acceleration is the rate at which an object's velocity changes, and in this case, the particle's velocity is increasing by 5.0 m/s every second. This means that its speed is increasing by 5.0 m/s every second, which aligns with the given answer.

Explanation

The correct answer is "The speed of the particle increases by 5.0 m/s during each second." This answer is supported by the statement that the particle is accelerated at a rate of 5.0 m/s2. Acceleration is the rate at which an object's velocity changes, and in this case, the particle's velocity is increasing by 5.0 m/s every second. This means that its speed is increasing by 5.0 m/s every second, which aligns with the given answer.

3. A basketball is tossed up into the air. What can you say about the top of the trajectory is

Acceleration is + 9.8 m/s/s, Velocity is 0 m/s

Acceleration is 0 m/s/s, Velocity is 9.8 m/s

Acceleration is - 9.8 m/s/s, Velocity is 0 m/s

Acceleration is + 9.8 m/s, Velocity is 9.8 m/s

Acceleration is 0 m/s, Velocity is 0 m/s

At the top of the trajectory, the basketball reaches its maximum height and momentarily stops moving vertically. This means that the velocity is 0 m/s. Since the basketball is moving upwards, the acceleration due to gravity acts in the opposite direction, causing a deceleration. Therefore, the acceleration is -9.8 m/s/s.

Explanation

At the top of the trajectory, the basketball reaches its maximum height and momentarily stops moving vertically. This means that the velocity is 0 m/s. Since the basketball is moving upwards, the acceleration due to gravity acts in the opposite direction, causing a deceleration. Therefore, the acceleration is -9.8 m/s/s.

4. The minimum takeoff speed for a certain airplane is 75 m/s. What is the acceleration for the plane must leave a 950m runway? Assume the plane starts from rest at one end of the runway.

1.5 m/s/s

3.0 m/s/s

4.5 m/s/s

6.0 m/s/s

7.5 m/s/s

Show your work on another paper for me to see. Pass in

Explanation

Show your work on another paper for me to see. Pass in

5.

This graph is a position / time graph.Which ones are moving to the left

A

D and E

A, B, C

A, B, E

E

The graph is a position/time graph, which means it shows the position of objects over time. The question asks which objects are moving to the left. Looking at the graph, we can see that object E is the only one with a negative slope, indicating that it is moving in the negative direction of the x-axis, which is to the left. Therefore, the correct answer is E.

Explanation

The graph is a position/time graph, which means it shows the position of objects over time. The question asks which objects are moving to the left. Looking at the graph, we can see that object E is the only one with a negative slope, indicating that it is moving in the negative direction of the x-axis, which is to the left. Therefore, the correct answer is E.

6. A Canadian goose flew 845 km from Southern California to Oregon with an average speed of 30.5 m/s. How long, in hours, did it take the goose to make this journey? Don't forget convert the km to meters.

27.7 h

66.1 h

462 h

8.33 h

7.7 h

The Canadian goose flew 845 km, which needs to be converted to meters by multiplying by 1000, resulting in 845,000 meters. The average speed of the goose was 30.5 m/s. To find the time it took for the journey, divide the distance by the speed: 845,000 meters / 30.5 m/s = 27,704.92 seconds. To convert this to hours, divide by 3600 (the number of seconds in an hour): 27,704.92 seconds / 3600 seconds/hour = 7.6958 hours, which rounds to 7.7 hours. Therefore, it took the goose 7.7 hours to make the journey.

Explanation

The Canadian goose flew 845 km, which needs to be converted to meters by multiplying by 1000, resulting in 845,000 meters. The average speed of the goose was 30.5 m/s. To find the time it took for the journey, divide the distance by the speed: 845,000 meters / 30.5 m/s = 27,704.92 seconds. To convert this to hours, divide by 3600 (the number of seconds in an hour): 27,704.92 seconds / 3600 seconds/hour = 7.6958 hours, which rounds to 7.7 hours. Therefore, it took the goose 7.7 hours to make the journey.

7. An object moving along a straight line is decelerating. Which one of the following statements concerning the object’s acceleration is necessarily true?

The value of the acceleration is positive.

The direction of the acceleration is in the same direction as the displacement.

The direction of the acceleration is in the direction opposite to that of the velocity.

The acceleration changes as the object moves along the line.

An object that is decelerating has a negative acceleration.

When an object is decelerating, it means that its velocity is decreasing. Since the direction of the acceleration is always in the same direction as the change in velocity, the acceleration will be in the opposite direction to that of the velocity. Therefore, the statement "The direction of the acceleration is in the direction opposite to that of the velocity" is necessarily true.

Explanation

When an object is decelerating, it means that its velocity is decreasing. Since the direction of the acceleration is always in the same direction as the change in velocity, the acceleration will be in the opposite direction to that of the velocity. Therefore, the statement "The direction of the acceleration is in the direction opposite to that of the velocity" is necessarily true.

8. A rock is thrown vertically upward from the surface of the earth. The rock rises to some maximum height and falls back toward the surface of the earth. Which one of the following statements concerning this situation is true if air resistance is neglected?

As the ball rises, its acceleration vector points upward.

The ball is a freely falling body for the duration of its flight.

The acceleration of the ball is zero when the ball is at its highest point.

The speed of the ball is negative while the ball falls back toward the earth.

The velocity and acceleration of the ball always point in the same direction

When air resistance is neglected, the only force acting on the rock is gravity. Gravity causes the rock to accelerate downwards, regardless of whether it is rising or falling. This means that the rock is in free fall throughout its entire flight, experiencing the same acceleration due to gravity. Therefore, the statement "The ball is a freely falling body for the duration of its flight" is true.

Explanation

When air resistance is neglected, the only force acting on the rock is gravity. Gravity causes the rock to accelerate downwards, regardless of whether it is rising or falling. This means that the rock is in free fall throughout its entire flight, experiencing the same acceleration due to gravity. Therefore, the statement "The ball is a freely falling body for the duration of its flight" is true.