K.C.S.E Physics Q & A - MODEL 2015PP1QN17

K.C.S.E Physics Q & A - MODEL 2015PP1QN17

​(a) Figure 11 shows a graph of pressure (p) against volume (y) for a fixed mass of a gas at constant temperature

​In the space provided, sketch the corresponding graph of p against 1/v. 
(b) Explain the pressure law using the kinetic theory of gases. 
(c) 20 cm3 of a gas exerts a pressure of 760 mmHg at 25°C. Determine the temperature of the gas when the pressure increases to 900 mmHg and the volume reduces to 15 cm3. 
(d) Figure 12 shows the path of a light ball projected horizontally.

The ball is then made to spin in an anticlockwise direction as it moves:
(i) on the same axis, sketch the new path of the ball. 
(ii) explain how the ball attains the new path

answers

​(b) -P/T = constant at constant volume
as temperature increases, the kinetic energy of the molecules increases  causing more collisions hence increased pressure.

(ii) Spinning causes high velocity of air above  the ball hence reduced pressure which causes the ball to rise higher.