9709 P42 - Jun 2013 - Q2
3607
A and B are two points 50 metres apart on a straight path inclined at an angle \(\theta\) to the horizontal, where \(\sin \theta = 0.05\), with A above the level of B. A block of mass 16 kg is pulled down the path from A to B. The block starts from rest at A and reaches B with a speed of 10 m s-1. The work done by the pulling force acting on the block is 1150 J.
- Find the work done against the resistance to motion.
The block is now pulled up the path from B to A. The work done by the pulling force and the work done against the resistance to motion are the same as in the case of the downward motion.
- Show that the speed of the block when it reaches A is the same as its speed when it started at B.
