Statement 1 : A particle is found to be at rest when seen from a frame S 1 and moving with a constant velocity when seen from another frame S 2 . We can say both the frames are inertial. Statement 2 : All frames moving uniformly with respect to an inertial frame are themselves inertial.

Statement -1 is True, Statement -2 is True ; Statement- 2 is NOT a correct explanation for Statement - 1

Statement- 1 is True, Statement-2 is True, Statement-2 is a correct explanation for Statement -1

Statement - 1 is True, Statement- 2 is False

Statement -1 is False, Statement -2 is True

HARD

Earn 100

Calculate the length contraction and orientation of a rod of length $5 m$ in a frame of reference which is moving with a velocity $0.6 c$ in a direction making on angle $30 °$ with the rod.

Important Questions on Laws of Motion

EASY

Physics>Mechanics>Laws of Motion>Frame of Reference

A block

A

takes

2 s

to slide down a frictionless incline of

30 °

and length

l

, kept inside a lift going up with uniform velocity

v

. If the incline is changed to

45 °

, the time taken by the block, to slide down the incline, will be approximately:

HARD

Physics>Mechanics>Laws of Motion>Frame of Reference

Two wooden blocks are moving on a smooth horizontal surface such that the block having mass $m$ remains stationary with respect to block of mass $M$ as shown in the figure below. The magnitude of the applied force $P$ is,

Question Image

EASY

Physics>Mechanics>Laws of Motion>Frame of Reference

A block of mass

M

placed inside a box descends vertically with acceleration

a

. The block exerts a force equal to one-fourth of its weight on the floor of the box. The value of

a

will be

EASY

Physics>Mechanics>Laws of Motion>Frame of Reference

A person is standing in an elevator. In which situation, he experiences weight loss ?

MEDIUM

Physics>Mechanics>Laws of Motion>Frame of Reference

A boy is standing on a weighing machine inside a lift. When the lift goes upwards with acceleration

\frac{g}{4},

the machine shows the reading

50 kg .

wt. When the lift goes downward with acceleration

\frac{g}{4},

the reading of the machine in

kg

wt

. would be

EASY

Physics>Mechanics>Laws of Motion>Frame of Reference

A man weighing

60 kg

is in a lift moving down with an acceleration of

1.8 {ms}^{- 2}

. The force exerted by the floor on him is?

MEDIUM

Physics>Mechanics>Laws of Motion>Frame of Reference

When a lift of mass

800 kg

is ascending with an acceleration of

5 m s^{- 2}

, the tension in its cable will be

______

take

(g = 10 m s^{- 2})

HARD

Physics>Mechanics>Laws of Motion>Frame of Reference

A particle is moving along the

x

-axis with its coordinate with time

t

given by

x (t) = 10 + 8 t - 3 t^{2} .

Another particle is moving along the

y

-axis with its coordinate as a function of time given by

y (t) = 5 - 8 t^{3} .

t = 1 s,

the speed of the second particle as measured in the frame of the first particle is given as

\sqrt{v} .

Then

v (i n m s^{- 1})

is ___________.

HARD

Physics>Mechanics>Laws of Motion>Frame of Reference

A girl drops an apple from the window of a train which is moving on a straight track with speed increasing with a constant rate. The trajectory of the falling apple as seen by the girl is

EASY

Physics>Mechanics>Laws of Motion>Frame of Reference

A plumb line is suspended from a ceiling of a car moving with horizontal acceleration

a

. What will be the angle of inclination with vertical?

MEDIUM

Physics>Mechanics>Laws of Motion>Frame of Reference

Two blocks

A

and

B

of masses

m_{A} = 1 k g

and

m_{B} = 3 k g

are kept on the table as shown in figure. The coefficients of friction between

A

and

B

0.2

and between

B

and the surface of the table is also

0.2 .

The maximum force

F

that can be applied on

B

horizontally, so that the block

A

does not slide over the block

B

is : [Take

g = 10 m / s^{2}

]

MEDIUM

Physics>Mechanics>Laws of Motion>Frame of Reference

A rocket is fired vertically from the earth with an acceleration of 2g, where g is the gravitational acceleration. On an inclined plane inside the rocket, making an angle

θ

with the horizontal, a point object of mass m is kept. The minimum coefficient of friction

μ_{m i n}

between the mass and the inclined surface such that the mass does not move is:

MEDIUM

Physics>Mechanics>Laws of Motion>Frame of Reference

A spring balance is attached to the ceiling of a lift. A man hangs his bag on the spring and the spring reads $49 N$ , when the lift is stationary. If the lift moves downward with an acceleration of $5 m s^{- 2}$ , the reading of the spring balance will be – $(g = 9.8 m s^{- 2})$

EASY

Physics>Mechanics>Laws of Motion>Frame of Reference

A man weighing

80 kg

, stands on a weighing scale in a lift that is moving upwards with a uniform acceleration of

5 m s^{- 2}

. What would be the reading on the scale?

(g = 10 m s^{- 2})

EASY

Physics>Mechanics>Laws of Motion>Frame of Reference

A lift is moving down with acceleration

a

. A man in the lift drops a ball inside the lift. The acceleration of the ball as observed by the man in the lift and a man standing stationary on the ground are respectively

MEDIUM

Physics>Mechanics>Laws of Motion>Frame of Reference

A bird is sitting in a large closed cage which is placed on a spring balance. It records a weight of 5N. The bird of mass 0.5 kg files upward in the cage with an acceleration of

2 m s^{- 2}

. The spring balance will now record a weight of......... at that moment?

MEDIUM

Physics>Mechanics>Laws of Motion>Frame of Reference

A piece of wire is bent in the shape of a parabola

y = k x^{2}

(

y -

axis vertical) with a bead of mass

m

on it. The bead can slide on the wire without friction. It stays at the lowest point of the parabola when the wire is at rest. The wire is now accelerated parallel to the

x -

axis with a constant acceleration

a

. The distance of the new equilibrium position of the bead, where the bead can stay at rest with respect to the wire, from the

y -

axis is -

MEDIUM

Physics>Mechanics>Laws of Motion>Frame of Reference

Represent the union of two sets by Venn diagram for each of the following.

$X = {x | x$ is a prime number between $80$ and $100}$

$Y = {y | y$ is an odd number between $90$ and $100}$

EASY

Physics>Mechanics>Laws of Motion>Frame of Reference

Statement 1 : A particle is found to be at rest when seen from a frame S₁ and moving with a constant velocity when seen from another frame S₂. We can say both the frames are inertial.

Statement 2 : All frames moving uniformly with respect to an inertial frame are themselves inertial.

EASY

Physics>Mechanics>Laws of Motion>Frame of Reference

A body of mass $50 kg$ is suspended using a spring balance inside a lift at rest. If the lift starts falling freely, the reading of the spring balance is

Calculate the length contraction and orientation of a rod of length 5 m in a frame of reference which is moving with a velocity 0.6 c in a direction making on angle 30° with the rod.

Important Questions on Laws of Motion

Learn and Prepare for any exam you want !

Calculate the length contraction and orientation of a rod of length $5 m$ in a frame of reference which is moving with a velocity $0.6 c$ in a direction making on angle $30 °$ with the rod.