Chapter 10 Quiz - Motion (Holt)

1. Average speed can be represented by the mathmatical expression

Distance/time

Distance x time

Time - distance

Time + distance

The correct answer is distance/time because average speed is calculated by dividing the distance traveled by the time taken. This ratio gives us the average rate at which an object is moving over a given period. The formula distance/time accurately represents this concept and allows us to calculate the average speed of an object.

Explanation

The correct answer is distance/time because average speed is calculated by dividing the distance traveled by the time taken. This ratio gives us the average rate at which an object is moving over a given period. The formula distance/time accurately represents this concept and allows us to calculate the average speed of an object.

2. The _______________ of an object consists of its speed and direction.

Velocity

Instantaneous speed

Average speed

Displacement

Velocity is a vector quantity that describes both the speed and direction of an object. It is different from speed, which only measures how fast an object is moving. Instantaneous speed refers to the speed of an object at a specific moment in time, while average speed is the total distance traveled divided by the total time taken. Displacement, on the other hand, refers to the change in position of an object from its starting point to its ending point. Therefore, velocity is the correct answer as it encompasses both speed and direction.

Explanation

Velocity is a vector quantity that describes both the speed and direction of an object. It is different from speed, which only measures how fast an object is moving. Instantaneous speed refers to the speed of an object at a specific moment in time, while average speed is the total distance traveled divided by the total time taken. Displacement, on the other hand, refers to the change in position of an object from its starting point to its ending point. Therefore, velocity is the correct answer as it encompasses both speed and direction.

3. When an object changes position relative to a reference point, the object is

Stationary

In motion

Moving at a constant speed

Moving at a constant velocity

When an object changes position relative to a reference point, it means that the object is not staying in one place and is instead moving. Therefore, the correct answer is "in motion".

Explanation

When an object changes position relative to a reference point, it means that the object is not staying in one place and is instead moving. Therefore, the correct answer is "in motion".

4. Displacement must always indicate

Velocity.

Direction.

Speed.

Time.

Displacement is a vector quantity that represents the change in position of an object. It includes both magnitude (distance) and direction. While velocity, speed, and time are related to displacement, they do not fully define it. Velocity is the rate of change of displacement with respect to time, speed is the magnitude of velocity, and time is the duration of displacement. Therefore, displacement must always indicate direction as well as magnitude.

Explanation

Displacement is a vector quantity that represents the change in position of an object. It includes both magnitude (distance) and direction. While velocity, speed, and time are related to displacement, they do not fully define it. Velocity is the rate of change of displacement with respect to time, speed is the magnitude of velocity, and time is the duration of displacement. Therefore, displacement must always indicate direction as well as magnitude.

5. A motorist travels at an average speed of 55.0 mi/h for 4.25 h. How far did he travel?

0.08 mi

13 mi

55 mi

234 mi

The motorist traveled at an average speed of 55.0 mi/h for 4.25 hours. To find the distance traveled, we can multiply the average speed by the time traveled: 55.0 mi/h * 4.25 h = 233.75 mi. Since the distance traveled cannot be a fraction of a mile, we round up to the nearest whole number, which is 234 mi.

Explanation

The motorist traveled at an average speed of 55.0 mi/h for 4.25 hours. To find the distance traveled, we can multiply the average speed by the time traveled: 55.0 mi/h * 4.25 h = 233.75 mi. Since the distance traveled cannot be a fraction of a mile, we round up to the nearest whole number, which is 234 mi.

6. A pitcher throws a baseball to home plate, a distance of 60.5 feet. The ball reaches home plate in 0.63 s. What is the velocity of the ball?

38 ft/s

38 ft/s toward home plate

96 ft/s

96 ft/s toward home plate

The velocity of the ball is 96 ft/s toward home plate because it covers a distance of 60.5 feet in 0.63 seconds. To calculate velocity, we divide the distance traveled by the time taken. In this case, 60.5 feet divided by 0.63 seconds equals approximately 96 ft/s. The direction of the velocity is toward home plate, as stated in the answer.

Explanation

The velocity of the ball is 96 ft/s toward home plate because it covers a distance of 60.5 feet in 0.63 seconds. To calculate velocity, we divide the distance traveled by the time taken. In this case, 60.5 feet divided by 0.63 seconds equals approximately 96 ft/s. The direction of the velocity is toward home plate, as stated in the answer.

7. A runner finishes a 500.0 m race in 1.6 min. What is her average speed?

0.19 m/s

5.2 m/s

96 m/s

312 m/s

The average speed of the runner can be calculated by dividing the total distance covered (500.0 m) by the total time taken (1.6 min). Converting the time to seconds (1.6 min = 96 seconds), we get an average speed of 5.2 m/s.

Explanation

The average speed of the runner can be calculated by dividing the total distance covered (500.0 m) by the total time taken (1.6 min). Converting the time to seconds (1.6 min = 96 seconds), we get an average speed of 5.2 m/s.

8. When the motion of an object is shown by a straight line on a distance-time graph with distance on the y-axis, the slope of the line is the

Distance traveled

Displacement

Speed

Time of travel

The slope of a line on a distance-time graph represents the rate at which distance is changing with respect to time. In other words, it represents the speed of the object. The steeper the slope, the faster the object is moving. Therefore, the correct answer is speed.

Explanation

The slope of a line on a distance-time graph represents the rate at which distance is changing with respect to time. In other words, it represents the speed of the object. The steeper the slope, the faster the object is moving. Therefore, the correct answer is speed.

9. On a bus traveling north at 20.0 m/s, a child walks south at 1.3 m/s. What is the childs resultant velocity?

18.7 m/s north

18.7 m/s south

21.3 m/s north

21.3 m/s south

The child is walking in the opposite direction to the bus, so their velocities are subtracted. The resultant velocity is therefore 20.0 m/s (bus velocity) - 1.3 m/s (child's velocity) = 18.7 m/s. Since the child is walking south, the resultant velocity is in the north direction.

Explanation

The child is walking in the opposite direction to the bus, so their velocities are subtracted. The resultant velocity is therefore 20.0 m/s (bus velocity) - 1.3 m/s (child's velocity) = 18.7 m/s. Since the child is walking south, the resultant velocity is in the north direction.

10. On a distance-time graph of an object's motion, distance is usually

Plotted on the x-axis

Greater than time

The dependent variable

Measured in ft/min

In a distance-time graph, the x-axis represents time and the y-axis represents distance. Therefore, distance is usually plotted on the x-axis. The graph shows how the distance changes over time, with time being the independent variable and distance being the dependent variable. The statement "greater than time" is incorrect and does not apply to the representation on a distance-time graph.

Explanation

In a distance-time graph, the x-axis represents time and the y-axis represents distance. Therefore, distance is usually plotted on the x-axis. The graph shows how the distance changes over time, with time being the independent variable and distance being the dependent variable. The statement "greater than time" is incorrect and does not apply to the representation on a distance-time graph.