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A block is kept on a frictionless inclined surface with angle of inclination $α$ . The incline is given an acceleration $a$ to keep the block stationary. Then $a$ is equal to –

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Important Questions on Laws of Motion

EASY

Physics>Mechanics>Laws of Motion>Types of Forces

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

HARD

Physics>Mechanics>Laws of Motion>Types of Forces

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,

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EASY

Physics>Mechanics>Laws of Motion>Types of Forces

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>Types of Forces

Which of the following represents fundamental forces of nature?

MEDIUM

Physics>Mechanics>Laws of Motion>Types of Forces

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>Types of Forces

The Nobel laureate ABDUS SALAM is known for discovery of

MEDIUM

Physics>Mechanics>Laws of Motion>Types of Forces

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})

EASY

Physics>Mechanics>Laws of Motion>Types of Forces

Three blocks A, B and C, of masses

4 kg, 2 kg

1 kg

and respectively, are in contact on a frictionless surface, as shown. If a force of

14 N

is applied on the

4 kg

block, then the contact force between A and B is:

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HARD

Physics>Mechanics>Laws of Motion>Types of Forces

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>Types of Forces

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?

EASY

Physics>Mechanics>Laws of Motion>Types of Forces

Let

G, W, S

and

E

be relative strengths of gravitational, weak nuclear, strong nuclear and electromagnetic forces. Identify the correct option

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Physics>Mechanics>Laws of Motion>Types of Forces

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 ___________.

EASY

Physics>Mechanics>Laws of Motion>Types of Forces

A curved road of diameter

1.8 km

is banked so that no friction is required at a speed of

30 m s^{- 1}

. What is the banking angle?

EASY

Physics>Mechanics>Laws of Motion>Types of Forces

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:

MEDIUM

Physics>Mechanics>Laws of Motion>Types of Forces

A ball of mass

m

is attached to the free end of an inextensible string of length

l

. Let

T

be the tension in the string. The ball is moving in horizontal circular path about the vertical axis. The angular velocity of the ball at any particular instant will be

MEDIUM

Physics>Mechanics>Laws of Motion>Types of Forces

An automobile moving with a speed of

36 km h^{- 1}

reaches an upward inclined road of angle

30 °,

its engine becomes switch off. If the coefficient of friction is

0.1

, then how much distance will automobile move before coming to rest?

EASY

Physics>Mechanics>Laws of Motion>Types of Forces

Two blocks $A$ and $B$ are placed one over the other on a smooth horizontal surface. The maximum horizontal force that can be applied on lower block $A$ , so that $A$ and $B$ move without separation is $49 N$ . The coefficient of friction between $A$ and $B$ is

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Physics>Mechanics>Laws of Motion>Types of Forces

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>Types of Forces

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>Types of Forces

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:

A block is kept on a frictionless inclined surface with angle of inclination α . The incline is given an acceleration a to keep the block stationary. Then a is equal to –

Important Questions on Laws of Motion

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A block is kept on a frictionless inclined surface with angle of inclination $α$ . The incline is given an acceleration $a$ to keep the block stationary. Then $a$ is equal to –