Part (a) was satisfactorily attempted by most candidates however; some confused work with moment of a force. Part (b) was poorly attempted. Part (c) showed that lessons are probably presented in an abstract manner as performance was poor. In part (d), the graph shape was correctly drawn by many but majority quoted the formula F = ma instead of deducing it.

The expected answers are:

(a)(i) Work is the product ofa force (applied) and the distance moved in the direction of the force
                        OR
The product of displacement and the component of the force in the direction of the displacement.
(ii) Power is the time rate at which energy is expended.
                        OR
Power is the time rate of doing work.

NOTE: Mathematical definitions are acceptable provided symbols are correctly defined.

(b)          Any correct difference
e.g.

Static Friction	Dynamic Friction
It exists between surfaces of stationary bodies	It exists between surfaces in relative motion

- For the same system the static frictional force is greater than dynamic frictional force

(c) The tyres have treads in them to provide better grip of roads due to increased friction thus preventing vehicles from skidding

(ii) Retardation d = slope (oflast segment of graph)

= v - 0
T3 - t2
= v
t3 - t2

F = md

= Mv/t3 - t2