Physics · NDA previous year questions

1. A.$P_1=P_2$
2. B.$P_1=4P_2$
3. C.$P_1=2P_2$
4. D.$P_1=8P_2$

A particle is moving in a circle of radius R with a constant speed v. Its average acceleration over the time when it moves over half the circle is :

1. A.$\frac{v^2}{R}$
2. B.$\frac{\pi v^2}{2R}$
3. C.$\frac{2v^2}{\pi R}$
4. D.0

Two forces of 5⋅0 N each are acting on a point mass. If the angle between the forces is 60°, then the net force acting on the point mass has magnitude close to :

1. A.8⋅6 N
2. B.4⋅3 N
3. C.5⋅0 N
4. D.6⋅7 N

A rectangle ABCD is kept in front of a concave mirror of focal length f with its corners A and B being, respectively, at distances 2f and 3f from the mirror with AB along the principal axis as shown in the figure. It forms an image A'B'C'D' in front of the mirror. What is the ratio of B'C' to A'D'?

1. A.1
2. B.2
3. C.$\frac{1}{2}$
4. D.$\frac{2}{3}$

Shown in the figure are two plane mirrors XY and YZ (XY ⊥ YZ) joined at their edge. Also shown is a light ray falling on one of the mirrors and reflected back parallel to its original path as a result of this arrangement. The two mirrors are now rotated by an angle θ to their new position X'YZ', as shown. As a result the new reflected ray is at an angle α from the original reflected ray. Then :

1. A.α = 0
2. B.α = θ
3. C.α = 2θ
4. D.α = 4θ

A railway wagon (open at the top) of mass $M_1$ is moving with speed $v_1$ along a straight track. As a result of rain, after some time it gets partially filled with water so that the mass of the wagon becomes $M_2$ and speed becomes $v_2$. Taking the rain to be falling vertically and the water stationery inside the wagon, the relation between the two speeds $v_1$ and $v_2$ is :

1. A.$v_1=v_2$
2. B.$\frac{1}{2}{M}_1{v}_1^2<\frac{1}{2}{M}_2{v}_2^2$
3. C.$M_1{v}_1=M_2{v}_2$
4. D.$M_1{v}_1<M_2{v}_2$

Which one of the following statements is not true for a flute, a musical instrument?

1. A.Momentum of waves on the blowing jet determines the loudness of the produced note.
2. B.Arrival time of the waves on the blowing jet determines the pitch of the produced note.
3. C.Sound comes from a vibrating column of air inside the flute.
4. D.Sound comes from a vibrating column of air inside as well as outside the flute.

A positive charge is moving towards south in a space where magnetic field is pointing in the north direction. The moving charge will experience :

1. A.a deflecting force towards north direction.
2. B.a deflecting force towards east direction.
3. C.a deflecting force towards west direction.
4. D.no deflecting force.

Which among the following is the popular method for manufacture of ammonia?

1. A.Ostwald's process
2. B.Haber-Bosch process
3. C.Electric furnace process
4. D.Electrolysis process

Copper sulphate crystals available in the market are blue coloured crystals. By careful heating, they turn to white colour. Which one of the following is responsible for the blue colour?

1. A.Oxygen
2. B.Nitrogen
3. C.Water
4. D.Hydrogen

Which one of the following astronomers proved that the Earth and other planets revolve around the Sun?

1. A.Copernicus
2. B.Kepler
3. C.Galileo
4. D.Newton

Sand falls vertically on a conveyor belt at a work rate of 0⋅1 kg/s. In order to keep the belt moving at a uniform speed of 2 m/s, the force required to be applied on the belt is :

1. A.0 N
2. B.0⋅2 N
3. C.1⋅0 N
4. D.2⋅0 N

The power required to lift a mass of $8\cdot 0\mathrm{kg}$ up a vertical distance of $4\mathrm{m}$ in $2\mathrm{s}$ is (taking acceleration due to gravity as $10m/{\mathrm{s}}^2$):

1. A.$80\mathrm{W}$
2. B.$160\mathrm{W}$
3. C.$320\mathrm{W}$
4. D.$640\mathrm{W}$

One block of $2\cdot 0\mathrm{kg}$ mass is placed on top of another block of $3\cdot 0\mathrm{kg}$ mass. The coefficient of static friction between the two blocks is $0\cdot 2$. The bottom block is pulled with a horizontal force F such that both the blocks move together without slipping. Taking acceleration due to gravity as $10m/{\mathrm{s}}^2$, the maximum value of the frictional force is :

1. A.$50\mathrm{N}$
2. B.$30\mathrm{N}$
3. C.$4\mathrm{N}$
4. D.$10\mathrm{N}$

A mass is attached to a spring that hangs vertically. The extension produced in the spring is 6 cm on Earth. The acceleration due to gravity on the surface of the Moon is one-sixth of its value on the surface of the Earth. The extension of the spring on the Moon would be:

1. A.6 cm
2. B.1 cm
3. C.0 cm
4. D.36 cm

In an electric circuit, a wire of resistance 10 Ω is used. If this wire is stretched to a length double of its original value, the current in the circuit would become :

1. A.half of its original value.
2. B.double of its original value.
3. C.one-fourth of its original value.
4. D.four times of its original value.

Which one of the following statements is true?

1. A.The force of gravity of the Earth on the Moon is greater than the force of gravity of the Moon on the Earth.
2. B.The force of gravity of the Moon on the Earth is greater than the force of gravity of the Earth on the Moon.
3. C.The force of gravity of the Earth on the Moon and of the Moon on the Earth are equal in magnitude and are in the same direction.
4. D.The force of gravity of the Earth on the Moon and of the Moon on the Earth are equal in magnitude but are in opposite directions.

An electric bulb is rated as 220 V and 80 W. When it is operated on 110 V, the power rating would be:

1. A.80 W
2. B.60 W
3. C.40 W
4. D.20 W

In the dispersion of white light by a common glass prism, which one among the following is correct?

1. A.Red light deviates the most because red light has highest speed in prism
2. B.Blue light deviates the most because blue light has highest speed in prism
3. C.Red light deviates the most because red light has lowest speed in prism
4. D.Blue light deviates the most because blue light has lowest speed in prism

Which one among the following is true for the speed of sound in a given medium?

1. A.Speed of sound remains same at all frequencies
2. B.Speed of sound is faster at higher frequencies
3. C.Speed of sound is slower at higher frequencies
4. D.Speed of sound is slower at higher wavelengths

Which one of the following telescopes contains only mirrors?

1. A.Galilean telescope
2. B.Keplerian telescope
3. C.Newtonian telescope
4. D.Schmidt telescope

The commercial unit of electrical energy is kilowatt-hour (kWh), which is equal to

1. A.$3.6\times 10^6$ J
2. B.$3.6\times 10^3$ J
3. C.$10^3$ J
4. D.1 J

Which one of the following statements regarding a current-carrying solenoid is not correct?

1. A.The magnetic field inside the solenoid is uniform.
2. B.The current-carrying solenoid behaves like a bar magnet.
3. C.The magnetic field inside the solenoid increases with increase in current.
4. D.If a soft iron bar is inserted inside the solenoid, the magnetic field remains the same.

A pressure cooker cooks food faster by

1. A.increasing the boiling point of water
2. B.decreasing the boiling point of water
3. C.increasing the melting point of water
4. D.decreasing the melting point of water

Which one of the following wavelengths corresponds to the wavelength of X-rays?

1. A.500 nm
2. B.5000 nm
3. C.100 nm
4. D.1 nm