Forces, Density And Pressure

Question 1

State the two conditions for a system to be in equilibrium.

Answer 1

1. No net resultant force in any direction.
2. No net moment about any pivot.

Question 2

Explain the origin of the upthrust of a fully sumerged cylinder.

Answer 2

Differences in pressures at the top and bottom surfaces of the cylinder.
Greater pressure at the bottom surface.

Question 3

System was in equilibrium. Anticlockwise moment was then decreased. How can equilibrium be reached again?

Answer 3

The force causing the clockwise moment can be decreased to decrease clockwise moment.
Alternatively the force producing anticlockwise moment may be increased

Question 4

Define Upthrust

Answer 4

Force exerted on a fully pr partially immersed body due to pressure differences b/w the top and bottom surfaces.