A rifle bullet loses $$\left(\frac{1}{25}\right)$$th of its velocity in passing through a plank. The least number of such planks required just to stop the bullet is

A uniform chain has a mass m and length $$l$$. It is held on a frictionless table with one-sixth of its length hanging over the edge. The work done in just pulling the hanging part back on the table is

What is the shape of the graph between speed and kinetic energy of a body?

A quarter horse power motor runs at a speed of 600 rpm. Assuming 60% efficiency, the work done by the motor in one rotation is