A student is riding the school bus. The bus stops as the driver applies the brakes. Which of these best describes this situation?
a
A force is changing the motion of the bus.
b
The school bus does not lose or gain kinetic energy.
c
There is no force acting on the busy, so it stops moving.
d
The bus is gaining energy because of friction.
a
A force is changing the motion of the bus.
When the driver applies the brakes, a force is exerted on the wheels of the bus due to friction between the brake pads and the wheels. This force opposes the forward motion of the bus, causing it to decelerate and eventually come to a stop. Thus, the bus's motion is changed by this force.