area A , which results in an upward force of P × A . Therefore, the piston is capable of supporting a large force (large weight of, say a car, or a truck, placed on the platform) F = PA = F A . By changing the force at A , the platform can be moved up or down. Thus, the applied force has been increased by a factor of A and this factor is the mechanical advantage of the device.
The example below clarifies it. Fig . (a) Whenever external pressure is applied on any part of a fluid in a vessel, it is equally transmitted in all directions. This indicates that when the pressure on the cylinder was increased, it was distributed uniformly throughout.
We can say whenever external pressure is applied on any part of a fluid contained in a vessel, it is transmitted undiminished and equally in all directions. This is another form of the Pascal’s law and it has many applications in daily life. A number of devices, such as hydraulic lift and hydraulic brakes, are based on the Pascal’s Fig . (b) Schematic diagram illustrating the principle behind the hydraulic lift, a device used to lift heavy loads.
Example . Two syringes of different cross-sections (without needles) filled with water are connected with a tightly fitted rubber tube filled with water. Diameters of the smaller piston and larger piston are . cm and .
cm respectively. (a) Find the force exerted on the larger piston when a force of N is applied to the smaller piston. (b) If the smaller piston is pushed in through . cm, how much does the larger piston move out?
Answer (a) Since pressure is transmitted undiminished throughout the fluid,