A 7 kg box is initially at the top of a plane inclined at 20 degrees to the horizontal. The box is given a slight push to start it moving down the plane with a velocity of 3 m/s . The coefficient of kinetic friction between the box and the incline is 0.3. The box slides to the bottom of the incline, which is 8 metres long.
(a) Calculate the initial potential energy of the box.
(b) Determine the work done by friction
(c) Use the work-energy principle to determine the velocity of the box at the bottom of the incline.