(a)(i) Work is the product of force and distance moved in the direction of the force
(ii) Power is the time rate of doing work. Unit of power is watts or J / sec.

(b) E = \(\frac{\text{Work output}}{\text{work input}}\) x 100% work input
E = \(\frac{\text{load x distance moved by load}}{\text{effort x distance moved by effort}}\)
But Ma = \(\frac{Load}{effort}\) and V.R = \(\frac{\text{distance moved by effort}}{\text{Effort distance moved by load}}\)
E = \(\frac{MA}{1} \times \frac{1}{VR}\) x 100%
E = \(\frac{MA}{V.R}\) x 100%

(c)(i) VR = \(\frac{1}{sin \theta}\) = \(\frac{1}{sin 45^o} = \frac{1}{0.2588}\) = 3.86

75% = \(\frac{9000}{Win}\) x 100%
Win = \(\frac{9000 \times 100}{75}\) = 12,000J
work input = 12000 J.
(d) At constant pressure, the number of collision per unit time is constant. An increase in temperature causes average Kinetic energy increases. The molecules then move faster. The volume therefore increases so as to maintain the number of collision per unit time.