(a) (i) Explain relative motion.
(ii) Two cars moving in opposite directions on the same straight road with velocities 80 km
h-1 and 60 km h-1 respectively pass each other at a point. Determine the velocity of
the first car relative to the second.
(b) (i) Define force
(ii) Classify the following forces as either contact forces or field forces; push; tension;
gravitational; electrostatic; reaction and magnetic.
(c) A body starts from rest and travels in a straight line for 2 seconds with uniform
acceleration of 1 ms-2. It then travels at a constant speed for some time before coming
to rest with a uniform retardation of 2 ms-2. The total distance covered by it is 1.5m
(i) Draw and label a velocity – time graph for the motion.
(ii) Calculate the:
(A) velocity attained after the first 2 seconds;
(B) total time taken for the journey.
Part(b) many candidates were unable to explain relative motion. Those that made effort lost marks because they did not mention the frame of reference in their explanation. Performance was average.
Part(b) majority of the responding candidates were able to define correctly force and classify the given forces as either contact forces or field forces.
Part(c) the drawing of the velocity –time graph did not pose any problem to the candidates; however, majority of those that attempted this question failed to calculate correctly the total time taken for the journey by the body.