Laws of motion practice · Mixed difficulty

In the above Question, if the string C is stretched slowly, then

Statement-I: Coefficient of friction can be greater than unity.
Statement-II: Force of friction is dependent on normal reaction and ratio of friction and normal reaction cannot exceed unity.

An object is thrown vertically upwards. At its maximum height, which of the following quantity becomes zero?

A particle is projected up an inclined plane with initial speed $v = 20\mathrm{m}{\mathrm{s}^{ - 1}}$ at an angle $\mathrm{\theta } = 30^\circ$ with plane. The component of its velocity perpendicular to plane when it strikes the plane is

A frictionless inclined plane of length l having inclination &theta; is placed inside a lift which is accelerating downward with an acceleration a($<g$) .&nbsp;If a block is allowed to move, down the inclined plane, from rest, then the time taken by the block to slide from top of the inclined plane to the bottom of the inclined plane is

Two bodies having the same mass 2 kg each have different surface areas $50\,{m^2}$ and $100\,{m^2}$ in contact with a horizontal plane. If the coefficient of friction is 0.2, the forces of friction that come into play when they are in motion will be in the ratio

Consider a small block placed with zero velocity on a rough convey or belt moving with constant velocity. The block eventually comes to rest with respect to belt.
Statement-1: Net work done by kinetic friction on belt is zero.
Statement-2: The kinetic energy of the belt does not change.

A weight ' $m g$ ' is suspended from the middle of a rope whose ends are rigidly clamped at the same level. The rope is no longer horizontal. What is the minimum tension required to completely straighten the rope?

An object is subjected to a force in the north-east direction. To balance this force, a second force should be applied in the direction

A particle is moving with a constant speed along a straight line path. A force is not required to

A spring balance and a physical balance are kept in a lift. In these balances equal masses are placed. If now the lift starts moving upwards with constant acceleration, then

Impulse is

A gun applies a force $F$ on a bullet which is given by $F=\left(100-0.5 \times 10^5 t\right) \mathrm{N}$. The bullet emerges out with speed $400 \mathrm{~m} / \mathrm{s}$. Then, find out the impulse exerted till force on bullet becomes zero.

A block of mass $50 \mathrm{~kg}$ slides over a horizontal distance of $1 \mathrm{~m}.$ If the coefficient of friction between their surfaces is $0.2,$ then work done against friction is

Statement-1: A man is standing on a bathroom scale. Suddenly he squats (sits down) with acceleration $a$. The scale reading will increase.
Statement-2: Man pushes down on the scale while squatting.

A bullet of mass 28 gm is fired from a rifle of mass 10 kg with a velocity of 100 m/s. The velocity of recoil of the rifle is

Assertion $[A]$ : A boy feels more pain when he falls down on a hard concrete floor than when he falls on the sand floor

Reason $[R]$: Every action has equal and opposite reaction. The time of impact of cement floor is smaller compared to that of sand floor

Shock absorbers are used in vehicles to reduce the magnitude of

A block of weight 200 N is pulled along a rough horizontal surface at constant speed by a force of 100 N acting at an angle of ${30^0}$ above the horizontal. The force required to push the same block on the same surface making the same angle with the horizontal, to maintain the same constant speed will be

The two factors on which the momentum of a body depends are_____ and _____

A particle of mass $m$ is released from top of a smooth hemisphere of radius $R$ placed on a horizontal surface. Find the contact force acting between the particle to the sphere when the line joining the particle to the centre of sphere makes an angle $60^{\circ}$ with upward vertical (Given ${g}=10$ $\mathrm{m} / \mathrm{s}^2)$

It was calculated that a shell when fired from a gun with a certain velocity and at an angle of elevation $\frac{{5\mathrm{\pi }}}{{36}}$ rad should strike a given target. In actual practice, it was found that a hill just prevented the trajectory. At what angle of elevation should the gun be to hit the target?

A bomb of mass 30 kg at rest explodes into two pieces of masses 18 kg and 12kg.The velocity of 18 kg mass is $6\;m{s^{ - 1}}.$ The kinetic energy of the other mass is

A 5000 kg of rocket is set for firing. If the exhaust speed of gases is $1000\,\,m{s^{ - 1}}$ with respect to rocket, how much gas must be ejected each second to supply the thrust needed to overcome weight of the rocket?

A boy of mass 50 kg climbs up a rope with an acceleration of $2\,\,m/{s^2}.$ What is the tension in the rope?

A satellite in force-free space sweeps stationary interplanetary dust at a rate $dM/dt = \alpha v$ where M is the mass, v is the velocity of the satellite and α is a constant. What is the deacceleration of the satellite

If a force of 260 N acts on a body the momentum required is 126 kg m/s. The period for which the force acts on the body is

External agencies like gravitational and magnetic forces ...X...
exerts force on a body from a distance.
Here, X refers to

When two blocks A and B coupled by a spring on a frictionless table are stretched and the released, then

For a body moving in a circular path, a condition for no skidding if $\mu$ is the coefficient of friction, is