Candidates’ performance in the part (a) of the question was fair. They were able to apply the appropriate equations of motion thus –
v = u+at, u = 32 m/s, a = -0.7ms-2 and t = 8.
Thus v = 32 – 5.6 = 26.4 m/s
S = ut + ½ at2 = 32(8) - ½ (o.7) 64 = 233.6m
In the part (b), candidates’ performance was very poor. They were not able to apply the momentum equation correctly. They were expected to show that if v is the velocity after collision, then
60 x5 – 50 x 16 = 60 x 4 + 50v where v = -740 = 14.8 m/s in its direction. The time it
50
will take P to come to rest after collision if it is travelling with a constant retardation of 0.25m/s2 is given by v = u + at, where v = 0. Therefore 0 = 14.8 - 0.25t. Hence t = 14.8
0.25
= 59.2 seconds.
