# Road to NDA : Daily Dose of Questions (Physics) - Day 1

By Dhruv Kumar|Updated : July 22nd, 2021

UPSC has already released the notification for NDA II 2021 which is scheduled to be conducted on 14th November 2021. Here we are publishing a large number of physics problems and questions. These physics questions are distributed among 7 sets of Questions for you which will be published in 7 days.

The first set (Set number 1) is being published on this post body itself and the rest of the sets (6 more) will be published in the coming days. The Standard of these sets is MEDIUM (not so hard). The questions provided in these sets are very important for the NDA exam. Attempt all these questions and let us know in the comment section. The winner of the quiz will be declared the next day. So here are 10 questions of physics:

UPSC has already released the notification for NDA II 2021 which is scheduled to be conducted on 14th November 2021. Here we are publishing a large number of physics problems and questions. These physics questions are distributed among 7 sets of Questions for you which will be published in 7 days.

The first set (Set number 1) is being published on this post body itself and the rest of the sets (6 more) will be published daily. The Standard of these sets is MEDIUM (not so hard). The questions provided in these sets are very important for the exam. Attempt all these questions and let us know in the comment section. The winner of the quiz will be declared the next day. So here are 10 questions of physics:

1.A particle moves in a circular orbit under the action of a central force attractive in nature. If the magnitude of the force varies inversely with the distance from the center r then how is the speed of particle related to r?

A. Varies directly with r
B. Varies indirectly with r
C. Does not depend on r
D. Varies directly with r2

2.If the normal reaction force is doubled then how does the coefficient of friction change?

A. Becomes half
B. Becomes double
D. Remains same irrespective of the normal reaction force

3.Match the eye defects with their suggested corrections. A. 1-b,2-c,3-d,4-a
B. 1-b,2-a,3-d,4-c
C. 1-a,2-b,3-c,4-d
D. 1-d,2-c,3-a,4-b

4.‘The removal of dust particles from a carpet upon beating it with a stick is an application of Newton’s II Law’

Choose the correct option.

A. True
B. False, application of I law
C. False, application of III law
D. Can’t say

5._____ remains unchanged despite the medium change for a sound wave. Fill in the blanks with the appropriate option.

A. Speed
B. Wavelength
C. Frequency
D. None of the above

-6.The increase in internal energy of a system is equal to the work done on the system. Identify the type of thermodynamic process.
A. Isobaric
B. Isochoric
C. Isothermal

7.What does the statement ‘Heat capacity of a substance is infinite’ imply?

A. It can give out infinite heat
B. It can take in infinite heat
C. Its temperature remains always constant despite change in heat amount
D. None of the above

8.Which of the following physical quantity is unitless?

A. Density
B. Inertial mass
C. Linear magnification
D. Time period

9.Which one of the following regarding the density of water at atmospheric pressure is correct?

A. Density of water at 4oC is 1000 kg,/m3.
B. Density of water at 0oC is 1000 kg/m3
C. Density of water at 0oC is 100 kg/m3
D. Density of water at 4oC is 10 kg/m3

10.The statement "friction force is a contact force

while magnetic force is a non-contact force" is

A. always true.
B. true only at 0o C
C. a false statement.
D. either true or false depending upon the temperature of the surroundings

### Solution:

1. Ans. C.

The central force in play here varies inversely with the distance r.

If the mass of the particle is m, its velocity v, then the central force will be This force varies indirectly with r   Where k is proportionality constant

Form above relation  This clearly shows that v is independent of r.

Hence C is the correct option.

2. Ans. D.

The coefficient of friction does not depend on the normal reaction force.

Hence D is the correct option.

3. Ans. B.

Myopia or short-sightedness is an eye defect where a person can see nearby objects clearly but not distant objects. A concave lens of appropriate focal length can be used to treat it.

Hypermetropia or long-sightedness is a vision defect where a person can see distant objects clearly but not nearby objects. It is treated by using a convex lens of appropriate focal length.

Cataract is a defect in which the lens inside the eye becomes cloudy. A cataract surgery is performed which replaces the lens with a better substitute.

Astigmatism is a defect where a person can not see the horizontal and vertical views of an object with the same clarity. It is corrected using a lens with a one cylindrical surface.

Hence B is the correct option.

4. Ans. B.

Newton’s I law of motion states that a body will continue being in a state of rest or motion until acted upon by an external force. When a dirty carpet is beaten by a stick, the dust particles which are at rest tend to move as force is being applied on the carpet by the stick. So they get removed in the process.

Hence B is the correct option.

5. Ans. C.

When a sound wave moves from a medium into some another medium, its frequency remains the same and everything else changes.

Hence C is the correct option.

6. Ans. D.

During this process, there will be no heat exchange between the system and the surroundings because  So this thermodynamic process is adiabatic.

Hence D is the correct option.

7. Ans. C.

The statement implies that there will be no change in the temperature of the substance no matter the amount of heat it gives or receives.

Hence C is the correct option.

8. Ans. C.

Density is the amount of mass contained per unit volume in a substance. Its dimensions are [ML-3]

Inertial mass is the mass of the body which determines its inertia in a linear motion. Its dimensions are [M]

Linear magnification is the ratio of the final size of the body to its initial size. It is a ratio of 2 physical quantities with same dimensions ∴ it is a unitless quantity.

The dimension of time period is [T].

Hence C is the correct option.

9. Ans. A.

Density is given by mass per unit volume. Mass of a body is always constant but volume changes as per physical conditions. Hence density varies with the change in physical conditions such as pressure, temperature, etc.

The density of water at atmospheric pressure is maximum at 4 degrees Celsius that is 1gram per milliliter.

1 gm/ml can also be written as 1gm/cm3

Since 1 ml=1cm3

Now, 1m3=106cm3 or 1cm3=10-6m3

1kg=1000gm or 1gm=10-3kg

Therefore, Hence option A is correct.

10. Ans. A.

The friction force is generated when two bodies rub each other, it opposes the motion, hence it is always a contact force.

Magnetic force is always a non-contact force as it opposes or attracts other charged particles, bodies, or other magnets.

Thanks

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