To solve for the final velocity of the box
when it reaches the bottom of the incline, we will use the work-energy
principle. The total work done on the box is the sum of the work done by
gravity and the work done by friction.
Forces acting on the box
1. Gravitational force component along the
incline:
This is the force that causes the box to
move down the incline.
2. Frictional force:
The normal force is:
The frictional force is:
This is the resistive force that opposes
the motion.
Work done on the box
1. Work done by gravity:
The displacement along the incline is .
The work done by the gravitational force is:
2. Work done by friction:
The work done by the frictional force is:
Since friction opposes the motion, this
work is negative:
Net work done
The net work done on the box is the sum of
the work done by gravity and the work done by friction: