K.C.S.E Physics Q & A - MODEL 2017PP1QN18

K.C.S.E Physics Q & A - MODEL 2017PP1QN18

(a) Figure 8 shows part of a hydraulic brake system.

​Describe how the systems works.
(b) State three conditions necessary for a driver to negotiate a bend on a flat level road at a relatively high speed. 
(c) Figure 9 shows two identical cans U and V each with a small opening at the top.
Different amounts of water were put into the cans and heated until the water started to boil.

​Explain what will be observed when both cans are then suddenly dipped into a cold water bath.

answers

(a) (i) The driver applies a force on the pedal.
 This force transmits pressure  the master cylinder fluid. 
 Equal pressure is transmitted to the wheel cylinder causing the pistons of the wheel cylinder to push brake shoe hence
 Pressing the brake pads that in turn press the wheel reducing its rotation. 
 When the applied force is removed, the return spring pulls back the shoe and pistons to the original position. 
(b) Higher friction (wider tyres, rougher road)
 Lower radius
 Higher mass
(c) U is observed to crush. 
It has more steam which when cooled creates a greater 
vacuum hence pressure causes  collapsing.