Which of the following is the best definition of motion?

A. The distance traveled by an object during a period of time
Incorrect. That is a definition of speed.

B. An object's speed
Incorrect. Speed is the distance traveled by an object during a period of time.

C. A change in an object's position over a period of time
Correct!

D. The time it takes for an object to move from one position to another
Incorrect. That is a definition of speed.

The difference between speed and velocity is that velocity includes —

A. friction
Incorrect. Friction is not the difference between speed and velocity.

B. distance
Incorrect. Distance is a factor in both speed and velocity.

C. time
Incorrect. Time is a factor in both speed and velocity.

D. direction
Correct! Velocity is speed in a given direction.

The rate at which an object's speed and/or direction changes is —

A. velocity
Incorrect. Velocity is speed in a given direction not the rate at which these factor change.

B. acceleration
Correct! Velocity is the rate at which an objects velocity (speed in a given direction) changes.

C. speed
Incorrect. Speed is the distance traveled by an object during a period of time.

D. distance
Incorrect. Distance is how far an object travels.

A car is traveling north at constant rate of 96 km/hr. This car would have no —

A. acceleration
Correct! Since the car is not changing direction or speed it has no acceleration.

B. velocity
Incorrect. We know both the speed and direction of the car so we could calculate the velocity.

C. speed
Incorrect. We know the car is traveling at a constant rate of 96 km/hr, so we know the car has speed.

D. mass
Incorrect. The car would have mass.

From the diagram above, you can tell that Car A and Car B do not have the same —

A. average speed
Incorrect. You cannot tell any information about the speed of the cars from the diagram.

B. constant speed
Incorrect. You cannot tell any information about the speed of the cars from the diagram.

C. velocity
Correct! The cars are moving in different directions, so they would not have the same velocity.

D. mass
Incorrect. You cannot tell any information about the mass of the cars from the diagram.