i) A book of length and breadth 20cm by 50 cm applies
a force of 25 N on the surface. Calculate the pressure
exerted by it.
ii) State the Pascal's Law.
Answers
Answer:
Let P
1
,P
2
and P
3
be the pressures exerted by the brick while resting on different faces.
The dimensions of the given brick are 20cm×10cm×5cm
Case (i) : When the block is resting on 20cm×10cmface.
Thrust acting= Weight of the brick
T=500gwt
Area of constant (A)=20cm×10cm
Pressure exerted (P
1
)
=
Area
Thrust
=
20×10
500
∴P
1
=2.5gwtcm
−2
Case (ii) : When the block is resting on 20cm×5cmface
Thrust= Weight of the brick
=500gwt
Area of constant (A)=20cm×5cm
Pressure exerted
(P
2
)=
Area
Thrust
=
20×5
500
∴P
2
=5gwtcm
−2
Case (iii) : When the block on 10cm×5cmface
Thrust= Weight of the brick =500g.wt.
Area of contact =10cm×5cm
Pressure=
Area
Thrust
=
10×5
500
P
3
=10gwtcm
−2
(ii) Pascal's law says that pressure applied to an enclosed fluid will be transmitted without a change in magnitude to every point of the fluid and to the walls of the container. The pressure at any point in the fluid is equal in all directions.