Practice MCQ Questions and answers on Physics-GK

41

In uniform circular motion, the linear velocity is perpendicular to

A) Radius B) Force C) Radius vector D) Momentum

Discuss

Answer & Solution

Answer: Option C

Solution:

In uniform circular motion, the linear velocity is perpendicular to radius vector.

42

Flywheel is an important part of a steam engine because it :

A) Accelerates the speed of the engine B) Helps the engine in keeping the speed uniform C) Decreases the moment of inertia D) Gives strength to the engine

Discuss

Answer & Solution

Answer: Option B

Solution:

A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia and thus resist changes in rotational speed, enabling the engine to run at a constant, uniform motion. In the Industrial Revolution, James Watt contributed to the development of the flywheel in the steam engine.

43

The following particles move with same kinetic energy. Which of them has maximum momentum ?

A) Electron B) Proton C) Deutron D) Alpha Particle

Discuss

Answer & Solution

Answer: Option D

Solution:

Since alpha particle has higher mass than electron, proton and deuteron, its momentum will be maximum.

44

Should cars have bumpers that collapse under impact?

A) Yes, since the offending car should get damaged and pay for the mistake B) No, since it would be very expensive to get the car repaired C) No, since the colliding car would then ram into the occupants and kill them D) Yes, since they help to absorb the impact of a collision and keep the occupants safe

Discuss

Answer & Solution

Answer: Option D

Solution:

In automobiles, a bumper is the front-most or rearmost part, ostensibly designed to allow the car to sustain an impact without damage to the vehicle’s safety systems. They are not capable of reducing injury to vehicle occupants in high-speed impacts, but are increasingly being designed to mitigate injury to pedestrians struck by cars.

45

When the speed of car is doubled, then what will be the braking force of the car to stop it in the same distance ?

A) Four times B) Two times C) Half D) One-fourth

Discuss

Answer & Solution

Answer: Option A

Solution:

Brake force, also known as Brake Power, is a measure of braking power of a vehicle. Suppose a car whose mass is ‘x’ and is braked from a speed of y km/hr to come to halt at a uniform retardation in z min. If the speed of the car is doubled in the same distance, then the braking force required to stop the car is four times the original speed i.e. ‘4v’. Note that all the parameters remain to be same.

46

The odometer guage indicates

A) The distance travelled by a vehicle B) The depth of the ocean C) Pitch length D) Frequency of the wave

Discuss

Answer & Solution

Answer: Option A

Solution:

The odometer or the odograph is an instrument used to indicate the distance travelled by the vehicle

47

If a force acts upon two objects at rest, and having different masses for the same amount of time, then which one of the following will be the same for both the objects?

A) Acceleration B) Kinetic Energy C) Velocity D) Momentum

Discuss

Answer & Solution

Answer: Option D

Solution:

If the same force is applied on two bodies of different masses for the same time, then the change produced in the momentum of the two bodies is also same .

48

Consider the following statements :
1. There is no net moment on a body which is in equilibrium.
2. The momentum of a body is always conserved.
3. The kinetic energy of an object is always conserved.
Which of the statements given above is/are correct?

A) 1, 2 and 3 B) 2 and 3 only C) 1 and 2 only D) 1 only

Discuss

Answer & Solution

Answer: Option C

Solution:

There is no net moment on a body which is in equilibrium and the momentum of a body is always conserved both are correct.

49

The rate of change of linear momentum of a body falling freely under gravity is equal to it's ________ ?

A) Kinetic Energy B) Weight C) Potential Energy D) Impulse

Discuss

Answer & Solution

Answer: Option B

Solution:

Rate of change of impulse equals the force . In case of freely falling body the only force is the weight.

50

According to the theory of relativity, which of the following always remains constant ?

A) Length of an object B) Time C) Space D) Velocity of light

Discuss

Answer & Solution

Answer: Option D

Solution:

The theory of relativity, or simply relativity, generally encompasses two theories of Albert Einstein: special relativity and general relativity. Concepts introduced by the theories of relativity include: Measurements of various quantities are relative to the velocities of observers. In particular, space and time can dilate. Space time: space and time should be considered together and in relation to each other. The speed of light is nonetheless invariant, the same for all observers.