Physics(Exams > Bitsat ) Questions and answers for exam Preparation

Exams > Bitsat

PHYSICS MCQs

Total Questions : 421 | Page 9 of 43 pages

A stone of mass m tied to a string of length `l` is rotated in a circle with the other end of the string as the centre. The speed of the stone is `v` . If the string breaks , the stone will

Move towards the centre
move away from the centre
move along a tangent
stop

Discuss Question

Answer: Option C. -> move along a tangent

Question 82.

A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle . The motion of the particle takes place in a plane . It follows that .

its velocity is constant
its acceleration is constant
its kinetic energy is constant
it does not move on a curcular path.

Discuss Question

Answer: Option C. -> its kinetic energy is constant

Question 83.

A block 'A' of mass 2 kg rests on a rough horizontal plank , the coefficient of friction between he plank and the block = 0,2 . If the plank is pulled horizontally with a constant acceleration of 3.96 m/`s^2`. The distance moved in metre by the block on the plank in 5 second after starting from rest is.

25
25 x 0.98
25 x 1.98
0

Discuss Question

Answer: Option A. -> 25

Question 84.

In circular motion

radial acceleration is non-zero
radial velocity is zero
body is in equilibrium
all of the above

Discuss Question

Answer: Option D. -> all of the above

Question 85.

In the above question . When `m_2` starts coming down:

`m_1/m_2 < sin theta - mu cos theta`
`m_1/m_2 > sin theta - mu cos theta`
`m_1/m_2 = sin theta - mu cos theta`
no sufficient information.

Discuss Question

Answer: Option B. -> `m_1/m_2 > sin theta - mu cos theta`

Question 86.

A car start from rest to cover a distance s. The coefficient of friction between the road and the tyres is `mu` . The minimum time in which the car can cover the distance is proportional to .

`mu`
`sqrt(mu)`
`1/mu`
`1/sqrt(mu)`

Discuss Question

Answer: Option D. -> `1/sqrt(mu)`

Question 87.

If a body of mass m is moving on a rough horizontal surface of coefficient of kinetic friction `mu`, the net electromagnetic force exerted by surface on the body is

`mg sqrt(1 + mu^2)`
`mu mg`
mg
`mg sqrt(1 - mu^2)`

Discuss Question

Answer: Option A. -> `mg sqrt(1 + mu^2)`

The net electromagnetic force = `sqrt(N^2 + f^2)`

But `N = mg , f = mu mg`

`rArr force = mg sqrt(1 + mu^2)`

Question 88.

A block is placed on a rough floor and a horizontal force F is applied on it . The force of friction by the floor on the block is measured for different values of F and a graph if plotted between them.

the graph is a straight line of slope `45^circ`
the graph is a straight line parallel to the F-axis
the graph is a straight line os slope `45^circ` for small F and a straight line parallel to the F=axis for large F
there is a small kink on the graph

Discuss Question

Answer: Option D. -> there is a small kink on the graph

Question 89.

A bicycle is in motion . When it is not pedaled, the force of friction exerted by the ground on the two wheels is such that it acts .

in the backward direction of the front wheel and in the forward direction on the rear wheel
in the forward direction on the front wheel and in the backward direction on rear wheel
in the backward direction on both the front and the rear wheels
in the forward direction on both the front and the rear wheels

Discuss Question

Answer: Option C. -> in the backward direction on both the front and the rear wheels

When the bicycle is being pedaled then during pedaling , the force is acting in the backward direction on the rear wheel and thus frictional force will act in the forward direction. The choice (C) is correct, when the bicycle is not pedaled.

Question 90.

Mark correct option or options

friction always opposes the motion of a body
friction only opposes the relative motion between furfaces
inetic friction depends on he speed of body when the speed of body is less than 10 m/s
the coefficient of friction is always less han or equal to one.

Discuss Question

Answer: Option B. -> friction only opposes the relative motion between furfaces