Physics Test

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Physics Test - 4

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Question 1
4 / -1

When a body moves in a circular path, no work is done by the force since

A
force and displacement are perpendicular to each other

B
the force is always away from the centre

C
there is no displacement

D
there is no net force

Solution
Question 2
4 / -1

A satellite is revolving in a circular orbit at a distance of 2620 km from the surface of Earth. What is the period of revolution of the satellite? (Given: Radius of Earth = 6380 km, Mass of Earth = 6 x 10²⁴ kg, G = 6.67 x 10^-11 Nm²/kg².

A
2.35 hr

B
5.3 hr

C
6.3 hr

D
9.2 hr

Solution
Question 3
4 / -1

The first law of motion is also known as the law of

A
inertia

B
momentum

C
force

D
impulse

Solution

Newton's first law of motion is also known as law of inertia.Newton's First Law states that an object will remain at rest or in uniform motion in a straight line unless acted upon by an external force. It may be seen as a statement about inertia, that objects will remain in their state of motion unless a force acts to change the motion.
Question 4
4 / -1

A
R=50 Ω, C=200 μF

B
R=50 Ω, L=2 mμ

C
R=400 Ω, C=50 μF

D
R= 50Ω, L=02 H

Solution
Question 5
4 / -1

The electron in a hydrogen atom makes a transition from n = n₁ to n = n₂ state. The time period of the electron in the initial state (n₁) is eight times that in the final state (n₂). The possible values of n₁ and n₂ are:

A
n₁= 8, n₂= 1

B
n₁= 4, n₂= 2

C
n₁ = 2, n₂ = 4

D
n₁ = 1, n₂ = 8

Solution
Question 6
4 / -1

A cricket bat is cut at the location of its centre of mass as shown. Then,

A
the bottom piece will have a greater mass

B
the two pieces will have same mass

C
the handle piece will have a greater mass

D
the mass of the handle piece will be double the mass of the bottom piece

Solution

As there is more material near the bottom end of the bat, the centre of mass of the bat is nearer the bottom end of the bat. The bat will balance horizontally on a knife edge placed at the centre of mass. Centre of the mass is the point about which the rigid body can be balanced. The centre of mass of the handle piece and the bottom piece are at distances d₁ and d₂ respectively from the centre of mass of the entire bat.

For the rotational equilibrium, we have M₁d₁ = M₂d₂ where M₁ and M₂ are the masses of the handle piece and the bottom piece respectively. The distance d₁ is greater than d₂ since the handle piece has thinner regions compared to the bottom piece.

Therefore, M₂ > M₁
Question 7
4 / -1

A ray incident at a point as an angle of incidence of 60^o, enters a glass sphere ofrefractive index, n= √3 and is reflected and refracted at the further surface of the sphere. The angle between the reflected and refracted rays at this surface is

A
50^o

B
60^o

C
90^o

D
40^o

Solution
Question 8
4 / -1

A round disc of moment of inertia 'I₂' about an axis perpendicular to its plane and passing through its centre is placed gently over another disc of moment of inertia 'I₁' rotating with an angular velocity 'ω' about the same axis. The final angular velocity of the combination of discs will be

A
[I₁/(I₁-I₂)]ω

B
ω

C
[I₁/(I₁+I2)]ω

D
[(I₁+I₂)/I₂]ω

Solution
Question 9
4 / -1

A bullet losses 1/30th of its velocity in passing through a plank. The least number of planks to stop the bullet would be

A
11

B
14

C
16

D
15

Solution
Question 10
4 / -1

A metal plate of area 10³ cm² rests on a layer of oil 6 mm thick. A tangential force of 10^-2 N is applied on it to move it with a constant velocity of 6 cm s^-1. The coefficient of viscosity of the liquid is

A
0.1 poise

B
0.5 poise

C
0.7 poise

D
0.9 poise

Solution