K.C.S.E Physics Q & A - MODEL 2012PP1QN16

K.C.S.E Physics Q & A - MODEL 2012PP1QN16

​(a) Figure 9 shows a trolley on a smooth surface being pulled by a constant force F.

​(i) On the axis provided, sketch the velocity-time graph for the motion of the trolley. 

​(ii) A parachute falling through the air attains terminal velocity after a short-time.
State the reason why it attains terminal velocity. 
(b) A ball of mass 200 g is thrown vertically upwards with velocity of 5 m/s. The air resistance is 0.4 N.
Determine;
(1) the net force on the ball as it moves up;
(take acceleration due to gravity g = 10 m/s2) 
(ii) the acceleration of the ball; 
(iii) the maximum height reached by the ball.
(c) Figure 10 shows the path of an object of mass m attached to a string of length r when whirled in a vertical circle at a constant speed V. A is the highest point on its path.

​(i) State the forces that provide the centripetal force on the object when it is at point A. 
(ii) Indicate with an arrow on the diagram the direction of the net force F acting on the object when it is at A. 

ANSWERS

(ii) Net force on the parachute becomes zero. (Sum of downward forces on it
should be equal to sum of upward forces)