Why Objects Float or Sink

Q.

The volume of a $500g$ sealed packet is $350c{m}^3$. Will the packet float or sink in water if the density of water is $1gc{m}^{-3}$? What will be the mass of the water displaced by this packet?

Q. The speed of a falling body increases continuously. Why?

1. The force acting on the body is in the direction of the fall.

2. The falling body is very light

3. No force acts on the falling body
4. Air exerts a frictional force on the falling body

Q. Which of the following forces prevents us from slipping on the ground?​

1. Gravitational force​
2. Frictional force​
3. Electrostatic force
4. Magnetic force​

Q.

What are the factors affecting buoyant force?

Q.

Two forces $F_1=5N$ and $F_2=8N$ acting at points A and B on a rod pivoted at a point O, such that OA = $2m$ and OB = $4m$. Calculate the total moment of the two forces about O.

1. 22 Nm anticlockwise

2. 42 Nm clockwise

3. 22 Nm clockwise

4. 42 Nm anticlockwise

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Calculate the volume of wood of mass 6000 kg if relative density of wood is 0.8.

Q. Calculate the buoyant force (in $N$) acting on a $250\text{g}$ rubik's cube of side length $8\text{cm}$, if only half of it is submerged in kerosene. The rubik's cube is hanging by a thread. Density of kerosene is $0.8\text{g}{\text{cm}}^{-3}$. Take $\text{g}=10\text{m}{s}^{-2}$.

1. 2.048

Q. <!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Calculate the volume of wood of mass 6000 kg if relative density of wood is 0.8.

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. $5gc{m}^{-3},float$
4. $1.0gc{m}^{-3},sink$

Q. Buoyant force acting on a body immersed in a liquid depends on the :

1. total depth of the liquid
2. density of the liquid
3. colour of a liquid
4. None of these

Q. A ball weighing 4 kg of density $4000kg{m}^{-3}$ is completely immersed in water of density ${10}^{3}kg{m}^{-3}$. Find the force of buoyancy on it in $N$. (Given $g=10m{s}^{-2}$)

1. $10N$
2. $0.1N$
3. None of the above
4. $1N$

Q. A cube of side $5$ $\text{cm}$ is immersed in water and then in saturated salt solution. In which case will it experience a greater buoyant force? If each side of the cube is reduced to $4$ $\text{cm}$ and then immersed in water, what will be the effect on the buoyant force experienced by the cube as compared to the first case of water?
Give reason(s) for each case.

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

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. The weight of a body is more than the buoyant force experienced by it, due to a liquid. The body will :

Q.

Under what condition does an object float on a liquid?

1. When density of the object is less than that of the liquid.
2. When the gravitational force on the object is more than the buoyant force acting on it.
3. When density of the object is more than that of liquid.
4. When the object displaces a volume of liquid more than its own volume.

Q.

A body floats or sinks due to difference in their:

1. Masses

2. Densities

3. Pressures

4. None of these

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.

In which direction does the buoyant force due to a liquid act?

1. Upward

2. In the direction of weight

3. Can't be determined

4. Downward

Q.

A block of plastic released under water come up to the surface of water because___________.

1. density of plastic < density of water

2. density of plastic > density of water

3. density of plastic = 0

4. density of plastic = density of water