A crate of mass 15kg is sliding on a smooth horizontal surface. Answer the following questions:
(i) State the formula for the kinetic energy of a moving body and name its SI unit.
(ii) Keeping the mass of the crate fixed, explain quantitatively how its kinetic energy will change if its speed is doubled.
(iii) The crate is initially moving with a speed of 2m/s. Calculate its kinetic energy. Then find the new kinetic energy when its speed becomes 4m/s and verify whether your calculation matches the explanation in part (ii).