Floating and Sinking

Q.

A cube of side 10 cm completely immersed in water experiences a buoyant force of 1000 N.

$g=10m/s^2$

1. True

2. False

Q. Question 20
Why does a block of plastic released under water come up to the surface of water?

Q.

Calculate the pressure at a depth of $50m$ below the surface of the sea. (The density of sea water is $1024kg{m}^{-3}$).

1. $512000Pa$

2. $51200Pa$
3. $5120Pa$
4. $512Pa$

Q. Which of the following conditions is true for a sinking body?

1. Buoyancy = Weight of the body
2. Buoyancy > Weight of the body
3. Weight of the displaced liquid < Weight of the body
4. Weight of the displaced liquid > Weight of the body

Q.

A body floats or sinks due to difference in their:

1. Densities

2. Pressures

3. None of these

4. Masses

Q. An object of mass $100g$ has a volume of $20c{m}^3$. Calculate the density of the object. Also, state whether the object will float or sink in water.

1. $5.0gc{m}^{-3},sink$
2. $2.0gc{m}^{-3},float$
3. $1.0gc{m}^{-3},sink$
4. $5gc{m}^{-3},float$

Q. When a body is immersed in kerosene, it sinks. Choose the correct option.

1. Density of kerosene > Density of body
2. Density of kerosene = Density of body
3. Density of kerosene < Density of body
4. Density of kerosene $\ne$ Density of body

Q. In which direction does the buoyant force act (if the weight is acting downwards)?

1. Upwards

2. Downwards

3. Perpendicular to the direction of the weight

4. At an acute angle to the downward direction

Q.

When a body's weight is greater than the Buoyant force, the body sinks with an acceleration equal to _____

• mass of the body = m
• weight of the body = W
• $F_b$ --> buoyant force

1. $\frac{m}{F_b-W}$

2. $\frac{m}{W-F_b}$

3. $\frac{F_b-W}{m}$

4. $\frac{W-F_b}{m}$

Q.

When does a body float on a fluid?

1. The weight of the fluid displaced > upthrust.

2. The weight of the fluid displaced = upthrust.

3. The weight of the fluid displaced < upthrust.

4. The weight of the body is heavy.