Physics
Answer
To apply brakes, the foot pedal is pressed due to which pressure is exerted on the liquid in the master cylinder P, so liquid runs out from the master cylinder P to the wheel cylinder Q.
As a result, the pressure is equally transmitted and undiminished through the liquid to the pistons B1 and B2 of the wheel cylinder Q. Therefore, the pistons B1 and B2 gets pushed outwards and brake shoes gets pressed against the rim of the wheel due to which the motion of the wheel retards.
Since, the area of cross section of piston A in the master cylinder P is less than that in the wheel cylinder Q, a small force applied at the foot pedal produces a large force on the pistons B1 and B2 of the wheel cylinder Q.
This is the force responsible for retarding the vehicle. It should be noted that due to transmission of pressure through liquid, equal pressure is exerted on all wheels of the vehicle connected to the pipe line R.
On releasing the pressure on the pedal, the spring pulls the brake shoes to it's original position and forces the piston's B1 and B2 to return back into the wheel cylinder Q. As a result the liquid runs back from the wheel cylinder Q to the master cylinder P and thus the brakes gets released.
Related Questions
Deduce an expression for the pressure at a depth inside a liquid.
The diagram in figure shows a device which makes use of the principle of transmission of pressure.
(i) Name the parts labelled by the letters X and Y.
(ii) Describe what happens to the valves A and B and to the quantity of water in the two cylinders when the lever arm is moved down.
(iii) Give reasons for what happens to the valves A and B in part (ii).
(iv) What happens when the release valve is opened ?
(v) What happens to the valve B in cylinder P when the lever arm is moved up ?
(vi) Give a reason for your answer in part (v)
(vii) State one use of the above device.
Explain the principle of a hydraulic machine. Name two devices which work on this principle.
Draw a simple diagram of a hydraulic jack and explain it's working.