A block is launched up an incline plane.After going up the plane,it slides back down to its starting position.The coefficient of friction between the block and the plane is 0.3.The speed of the block when it reaches the starting position on the trip down:
A)is the same as the launching speed.
B)is less than the launching speed.
C)is more than the launching speed.
D)cannot be compared to the launch speed with the information given.

Question

Quizplus · Accepted Answer

The speed of the block when it reaches the starting position on the trip down will be less than the launching speed due to the presence of friction. As the block goes up the incline, some of its initial kinetic energy is converted into potential energy. When it comes back down, it will have less potential energy than it did when it was launched, which means it will have less kinetic energy and hence a lower speed. The frictional force acting on the block as it slides down the plane further reduces its speed. Therefore, option B is the best choice.

A Block Is Launched Up an Incline Plane