With the help of an activity prove that the force acting on a smaller area exerts a larger pressure?
With the help of an activity prove that the force acting on a smaller area exerts a larger pressure?
Consider a block of wood kept on a table top. The mass of the wooden block is 5 kg. Its dimension is 40 cm x 20 cm x 10 cm.
Now, we have to find the pressure exerted by the wooden block on the table top by keeping it vertically and horizontally.
The mass of the wooden block = 5 kg
Weight of the wooden block applies a thrust on the table top
Thrust = F = m x g
= 5 kg x 9.8 m/s2 = 49 N
Case a: When the wooden box is kept vertically with sides 20 cm x 10 cm.
Area of a side = length x breadth
= 20 cm x 10 cm
= 200 cm2 = 0.02 m2
Pressure = \(\frac{Thrust}{Area}\) = \(\frac{49 N}{0.02 m^2}\) = 2450 N/m2
Case b: When the block is kept horizontally with side 40 cm x 20 cm
Area = length x breadth
= 40 cm x 20 cm
= 800 cm2 = 0.08 m2
Pressure = \(\frac{Thrust}{Area}\) = \(\frac{49 N}{0.08 m^2}\) = 612.5 N/m2
∴ The pressure exerted by the box in case (a) is more as compared to the pressure exerted in case (b).
The area is reduced and the pressure exerted is more.
This shows that pressure ∝ 1/area.
Pressure will be larger if the area is reduced.
Application:
- Nails have pointed tips.
- Knives have sharp edges.
- Needles have pointed tips.
-
A 1 kg sheet of tin sinks in water but if the same sheet is converted into a box or boat, it floats. Why?
2 years ago
-
A boy gets into a floating boat. (a) What happens to the boat? (b) What happens to the weight of water displaced?
2 years ago
-
When a golf ball is lowered into a measuring cylinder containing water, the water level rises by 30 cm^3 when the ball is completely submerged.
2 years ago
-
A beaker full of water is suspended from a spring balance. Will the reading of the balance change: (a) if a cork is placed in water? (b) if a piece of heavy metal is placed in it? Give reasons for your answer.
2 years ago
-
If a fresh egg is put into a beaker filled with water, it sinks. On dissolving a lot of salt in the water, the egg begins to rise and then floats. Why?
2 years ago
- 321 Forums
- 27.3 K Topics
- 53.8 K Posts
- 0 Online
- 12.4 K Members