1.
Jenna knows that a friend runs 100m in 8s. She could use this to calculate her friend's
Correct Answer
C. Speed
Explanation
Jenna can use the information that her friend runs 100m in 8 seconds to calculate her friend's speed. Speed is defined as the distance traveled divided by the time taken, so by dividing 100m by 8s, Jenna can determine her friend's speed.
2.
Motion is a change in
Correct Answer
A. Position over time
Explanation
Motion is defined as a change in position over time. This means that an object is considered to be in motion if its position changes with the passage of time. The other options - speed, velocity, and acceleration - are all related to motion but do not encompass the complete definition. Speed refers to the rate at which an object moves, velocity includes both the speed and direction of motion, and acceleration refers to the rate at which an object's velocity changes over time. Therefore, the correct answer is position over time.
3.
Dan sits in a moving car. As he looks out the window, another car is right next to his. When he looks again, the other car is still right next to his. Which of the following is true?
Correct Answer
C. The other car is moving with the same speed as Dan's car
Explanation
The fact that the other car remains right next to Dan's car indicates that they are moving with the same speed. If the other car was moving faster, it would have overtaken Dan's car, and if it was moving slower, it would have fallen behind. Therefore, the only logical conclusion is that the other car is moving with the same speed as Dan's car.
4.
Bill walks 100m in 50s, moving at different speeds. Dividing 100m by 50s gives you Bill's
Correct Answer
B. Average speed
Explanation
The correct answer is average speed because dividing the distance (100m) by the time (50s) gives us the average speed at which Bill was moving. This calculation does not take into account any changes in speed or direction during the 50s, but simply gives us the overall average speed for the entire distance traveled.
5.
Susie is riding her bicycle. She begins pedaling harder. What do you predict will happen?
Correct Answer
C. Her speed will increase
Explanation
When Susie begins pedaling harder on her bicycle, it indicates that she is applying more force to the pedals. This increased force will result in an increase in the net force acting on the bicycle, causing it to accelerate. As a result, her speed will increase. Velocity refers to the speed of an object in a given direction, and since the direction is not specified in the question, we can assume that it remains constant. Therefore, the correct answer is that her speed will increase.
6.
Speed in a specific direction is
Correct Answer
D. Velocity
Explanation
Velocity is defined as the rate at which an object changes its position in a specific direction. It includes both the speed and direction of the object's motion. Acceleration, on the other hand, refers to the rate at which an object changes its velocity. Distance is the total length traveled by an object, regardless of direction. Position refers to the location of an object in space. Therefore, velocity is the correct answer as it specifically refers to speed in a specific direction.
7.
Sara walked north at 100 m/s. Scott had a different velocity but the same speed. He could have walked
Correct Answer
C. West at 100 m/s
Explanation
Scott had the same speed as Sara, which means he covered the same distance in the same amount of time. Since Sara walked north at 100 m/s, Scott could have walked west at 100 m/s to cover the same distance in the same time. This is because north and west are perpendicular directions and Scott's velocity in the west direction would create a right triangle with Sara's velocity in the north direction, resulting in the same overall speed.
8.
Jess drives at a steady velocity. Her acceleration is
Correct Answer
A. Equal to zero
Explanation
When Jess drives at a steady velocity, it means that her speed and direction of motion do not change over time. In other words, there is no change in velocity. Acceleration, by definition, is the rate of change of velocity. Since there is no change in velocity when Jess drives at a steady velocity, her acceleration is equal to zero.
9.
Acceleration measures a change in
Correct Answer
D. Velocity
Explanation
Acceleration measures a change in velocity. Velocity is a vector quantity that includes both magnitude and direction, whereas location, direction, and position are all related to the position of an object in space. Therefore, acceleration is specifically concerned with changes in an object's velocity, which includes changes in both speed and direction.
10.
On a velocity time graph, a line that is slanted down from left to right shows
Correct Answer
A. Negative acceleration
Explanation
A line that is slanted down from left to right on a velocity-time graph indicates negative acceleration. This means that the object is slowing down or decelerating. The steeper the slope of the line, the greater the magnitude of the negative acceleration.
11.
During which time interval was the car's speed zero?
Correct Answer
D. 10-30 seconds
Explanation
During the time interval of 10-30 seconds, the car's speed was zero.
12.
What was the car's average speed over the 6 seconds shown? Use the formula for speed. S=d/t
Correct Answer
B. 5 m/s
13.
When was the car's speed greatest?
Correct Answer
C. 2-4 seconds
Explanation
During the time interval of 2-4 seconds, the car's speed was at its highest. This means that within this specific time frame, the car was accelerating the most or reaching its maximum speed.
14.
Which car has the greater acceleration between 20 and 40 seconds?time20s40s60s80sCar A30 m/s35 m/s40 m/s35 m/sCar B25 m/s35 m/s40 m/s50 m/s
Correct Answer
B. Car B
Explanation
Car B has the greater acceleration between 20 and 40 seconds because its velocity increases from 25 m/s to 35 m/s, while Car A's velocity remains constant at 30 m/s during that time interval.
15.
Find the acceleration of Car A between 20s and 60s. time20s40s60s80sCar A30 m/s35 m/s40 m/s35 m/s
Correct Answer
D. .25 m/s2
Explanation
The acceleration of Car A between 20s and 60s can be calculated by finding the change in velocity and dividing it by the change in time. The initial velocity at 20s is 30 m/s and the final velocity at 60s is 40 m/s. The change in velocity is 40 m/s - 30 m/s = 10 m/s. The change in time is 60s - 20s = 40s. Dividing the change in velocity by the change in time gives us 10 m/s / 40s = 0.25 m/s^2. Therefore, the acceleration of Car A between 20s and 60s is 0.25 m/s^2.