(a) You wish to move a square box (0.3m by 0.3m) by 1m across a pavement. Given that the box has of a mass of 80kg, by which way, rolling or sliding, will you need more energy? Why? The coefficient of friction between the pavement and the box is 0.6 (Hint: consider the energy used to roll equals to the work done to raise the centre of mass). Gravitational acceleration g = 9.81m/s2 (b) Based on the above, what would be the value of the coefficient of friction to yield the same energy by sliding and rolling when moving the box by the same length?