A motorcycle is being driven on a road moving north at 40 miles per hour. A car is driving on the same road moving south at 40 miles per hour. Which of the following is true? a The motorcycle and the car are moving in opposite directions, so their speeds are different. b The motorcycle and the car are moving in opposite directions, so their velocities are different. c The motorcycle and car are moving at the same velocity and the same speed. d The motorcycle and car are moving at the same velocity but different speeds.
b) The motorcycle and the car are moving in opposite directions, so their velocities are different.
Explanation:
Speed and velocity are related concepts in physics, but they are not the same thing. Speed is a scalar quantity that refers to how fast an object is moving. It is the rate of change of distance with respect to time and has no direction associated with it. Velocity is a vector quantity that includes both speed and direction. The magnitude of the velocity vector gives the speed of the object.
Since the motorcycle and the car are both traveling at 40 miles per hour, they have the same speed. However, because they are moving in opposite directions (the motorcycle is heading north and the car is heading south), their velocities are different. The direction is an essential component of velocity, therefore, the motorcycle's velocity vector is directed north while the car's velocity vector is directed south.