Practice MCQ Questions and answers on Physics-GK

31

The wall of a dam is broader at the base

A) Because streamlining is required B) To withstand pressure that increases with depth C) To withstand pressure that increases in a horizontal plane D) To withstand pressure that is increased with atmospheric pressure

Discuss

Answer & Solution

Answer: Option B

Solution:

The pressure applied to walls of the dam will be a function of the amount of water that is over that particular point on the wall. So water pressure is very large at the bottom due to its large depth. That's why dams are constructed thicker at their bottoms than at their tops.

32

It is easy to burst a gas-filled balloon with a needle than with a nail. It is because

A) Nail is more longer than needle. B) Nail exerts more pressure than needle on the balloon. C) Needle exerts more pressure than nail on the balloon. D) Gas is reactive with the needle.

Discuss

Answer & Solution

Answer: Option C

Solution:

It is easy to burst a gas filled balloon with a needle than with a nail. It is because needle exerts more pressure on the bottom.

33

The force exerted on an object is 200 N and its mass is 100 kg. Find the acceleration of the object.

A) 2 m/s B) 2 m C) 2 m/sq.s D) 2 s

Discuss

Answer & Solution

Answer: Option C

No explanation is given for this question. Let's Discuss on Board

34

The spokes used in the wheel of a bicycle increase its

A) Moment of inertia B) Velocity C) Acceleration D) Momentum

Discuss

Answer & Solution

Answer: Option A

Solution:

A spoke is one of some number of rods radiating from the center of a wheel (the hub where the axle connects), connecting the hub with the round traction surface. Metal spokes used in bicycles also increase the moment of inertia.

35

It is difficult to cook rice

A) At the top of a mountain B) At the sea level C) Under a mine D) Same anywhere

Discuss

Answer & Solution

Answer: Option A

Solution:

At high altitude pressure is low and therefore the boiling point is also low. In this case, water starts boiling below its boiling point but rice cooks at 100. So, it is difficult to cook rice at high altitudes.

36

Energy per unit volume is dimensionally equal to

A) Pressure B) Force C) Density D) Work

Discuss

Answer & Solution

Answer: Option A

Solution:

Energy per unit volume is dimensionally equal to pressure.

37

To open a door easily, the handle should be fixed

A) Near the hinges B) Away from mid-point opposite to hinges C) In the middle D) None of these

Discuss

Answer & Solution

Answer: Option D

Solution:

None of the above

38

Water boils at a lower temperature on the hills because

A) It is cold on the hills B) There is less carbon dioxide on the hills C) There is a decrease in air pressure on the hills D) There is less oxygen

Discuss

Answer & Solution

Answer: Option C

Solution:

The boiling point of water is lower at higher altitudes due to the decreased atmospheric pressure. A liquid boils when its vapour pressure exceeds the local total pressure. As the atmospheric pressure drops, the Vapour pressure increases more than the local pressure at an even lower temperature.

39

The force exerted by a magnet is an example of ________

A) Non-contact force B) Muscular force C) Contact force D) Electrostatic force

Discuss

Answer & Solution

Answer: Option A

Solution:

The force exerted by a magnet is an example of Non-contact force.

40

A man standing close to the platform at a railway station experiences a pulling force towards a fast moving train because of ________ .

A) Gravitational force between train and man B) Illusion of the man C) The centripetal force D) Pressure difference due to fast moving air in between

Discuss

Answer & Solution

Answer: Option D

Solution:

When a fast-moving train passes a man standing on the platform at rest, the air between train and person also moves with greater speed. This rapidly moving air, by Bernoulli's principle will have a lower pressure than the still air a few feet away.