1.
When an object changes position relative to a reference point, the object is
Correct Answer
B. 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".
2.
Average speed can be represented by the mathmatical expression
Correct Answer
A. Distance/time
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.
3.
The _______________ of an object consists of its speed and direction.
Correct Answer
A. Velocity
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.
4.
A runner finishes a 500.0 m race in 1.6 min. What is her average speed?
Correct Answer
B. 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.
5.
A motorist travels at an average speed of 55.0 mi/h for 4.25 h. How far did he travel?
Correct Answer
D. 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.
On a distance-time graph of an object's motion, distance is usually
Correct Answer
B. Greater than time
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.
7.
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?
Correct Answer
D. 96 ft/s toward home plate
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.
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
Correct Answer
C. 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?
Correct Answer
A. 18.7 m/s north
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.
Displacement must always indicate
Correct Answer
B. Direction.
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.