Part (a). This question was very popular among the candidates and it was fairly well attempted. However, some candidates could not correctly list all the three facts. Few of the candidates mixed up their answers with centre of gravity.
Part (b) many candidates only listed the object without the action word (verb) to give it the projectile sense e.g discuss instead of discuss thrown. Most candidates did not
know that the object becomes a projectile only when it is in motion (action).
Part (c). Performance was below average as many candidates plotted the points but
did not start it from the origin as required in the question. Many even drew a straight
line to join the points instead of a smooth curve.
Part (d). Most candidates answered this part correctly. Performance was above
average.
The expected answers are:
- Acceleration of free fall due to gravity
e.g - its magnitude reduces with altitude (height)
- at equator, its value is about 10ms-2
- its value on earth is about 6 times that on the moon/
greater than that on the moon)
- It is a vector quantity.
(b) Objects considered as projectiles
In Sports In Warfare
e.g - Discuss thrown e.g. Missiles fired/thrown
- Short-put projected - Bullets fired
- Javelin projected - Arrow shot/thrown
- Golf ball hit.
- kicked football into the air
I) Axes correctly distinguished (II) Reasonable scales (Both axes) (III) Five points correctly plotted (IV) Curve of best fit
(ii) H correctly shown on graph
Correctly recorded
(d) v = u + at
15 = 10 + a x 3
a = = 1.67 ms-2
F = ma
= 60 x 1.67
= 100N
