Sink or Float

Q.

A ship begins to submerge more as it sails from sea water to river water.

1. True

2. False

Q.

Why do object like metals or stones sink in water?

Q.

A block of wood just floats in water. If the water is heated, the block will

1. float with some part outside water

2. keep bouncing up and down

3. just float in water

4. sink

Q.

An empty plastic bottle floats, while a plastic bottle filled with sand sinks in water because

1. density of empty plastic bottle is more than density of water

2. density of empty plastic bottle is more than density of plastic bottle filled with sand

3. density of empty plastic bottle is less than density of water

4. density of empty plastic bottle is less than density of plastic bottle filled with sand

Q. The following figure shows a body floating in three different liquids A, B, and C at different levels.

Which liquid has the least density?

1. Liquid B
2. Liquid C
3. All have the same density
4. Liquid A

Q. $3$ objects of different shapes cylindrical, cubic and conic having same density and same volume are immersed in the water as shown in the figure. Which object will experience the most upthrust in the water?

1. Cylindrical object
2. Cubic object
3. Conic object
4. Upthrust will be equal for all three objects.

Q.

A combination of wood and iron, just floats on the water at room temperature. What will you observe when the water is heated?

1. The combination will float below the surface of liquid.

2. The combination will float on the surface of the liquid.

3. The combination will sink.

4. None of these.

Q. Mark the object(s) that float(s) in the water.

1. Empty plastic bottle
2. Piece of glass
3. Oil
4. Wood

Q.

Does weight affect buoyancy?p

Q.

Floating and sinking of an object depends on:

1. mass of the fluid and the object

2. volume of the fluidand the object

3. density of object and fluid

4. density of fluid only

Q.

The apparent weight of a body in a fluid is :

1. equal to weight of fluid displaced

2. volume of fluid displaced

3. difference between its weight in air and weight of fluid displaced

4. none of the above

Q.

A combination of wood and iron, just floats in the water at room temperature. Explain what you will observe when the water is heated.

1. The combination will still float with same position.

2. The combination will float on the surface of the liquid.

3. The combination will sink.

4. None of the above.

Q.

Plimsoll lines are marked on the hull of a ship for decorative purposes.

1. True
2. False

Q.

A piece of wood has dimensions $1m\times 2m\times 3m$ and a mass of $2kg$. What is the density of wood and will the piece float in water?

$[{\rho }_{water}$ = 1000 $kg{m}^{-3}]$

1. 0.33 x 10^-3, NO

2. 0.33, YES

3. 3, YES

4. 3 x 10^-3, NO

Q.

If we throw a wooden log and a metal of same mass and weight, then the metal will sink easily but the wooden log will float on water. Why?

Q.

A body sinks when immersed in kerosene. What relation can be established between the density of body and kerosene?

1. Density of kerosene > Density of body

2. Density of kerosene = Density of body

3. Density of kerosene < Density of body

4. None of these

Q.

A block of iron sinks in fluid A but floats in another liquid B, this is because:

1. Density of fluid A = Density of fluid B

2. Density of fluid A < Density of fluid B

3. Density of fluid A > Density of fluid B

4. Can’t be determined

Q. A buoy is held inside water contained in a vessel by tying it with a thread to the base of the vessel. Tension in thread acts in which direction?

1. Vertically up
2. Vertically down
3. Horizontally
4. There is no tension in the string

Q.

A block of iron sinks in fluid A but floats in another liquid B, this is because:

1. Density of fluid A = Density of fluid B

2. Can’t be determined

3. Density of fluid A > Density of fluid B

4. Density of fluid A < Density of fluid B

Q.

A body floats or sinks due to difference in their:

1. Pressures

2. Masses

3. Densities

4. None of these

Q. What is the meaning of density in terms of Archimedes principle? [3 Marks]

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

1. Upward
2. At an acute angle to the downward direction
3. Perpendicular to the direction of the weight
4. Downward

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.

A combination of wood and iron, just floats on the water at room temperature. What will you observe when the water is heated?

1. The combination will sink.

2. None of these.

3. The combination will float on the surface of the liquid.

4. The combination will float below the surface of liquid.

Q.

An object of mass 100 g has a volume of $20gc{m}^{-3}$. Calculate the density of the object. 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. $1.0c{m}^{-3},sink$

Q.

A block of iron sinks in fluid A but floats in another liquid B, this is because:

1. Density of fluid A > Density of fluid B

2. Density of fluid A = Density of fluid B

3. Density of fluid A < Density of fluid B

4. Can’t be determined

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

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. What happens to the buoyant force acting on an airship as it rises in the air?

1. Buoyant force first increases then shows decrease
2. Buoyant force increases
3. Buoyant force decreases
4. Buoyant force remains constant