Laws of motion practice · Mixed difficulty

Three concurrent co-planar forces 1 N,2 N and 3 N acting along different directions on a body

A body moves along a circular path of radius 5 m. The coefficient of friction between the surface of path and the body is 0.5. The angular velocity, in radians/sec, with which the body should move so that it does not leave the path is $\left( {\mathrm{g} = 10\mathrm{m}{\mathrm{s}^{ - 2}}} \right)$

Assertion (A) : Speed of a particle moving in a circle varies with time as, $v=(4 t-12)$. Such type of circular motion is not possible.

Reason (R) : Speed cannot change linearly with time.

Consider the following two statements
I. Linear momentum of a system of particles is zero.
II. Kinetic energy of a system of particles is zero. Then

Which one of the following is not a contact force?

The velocity of a body of mass 20 kg decreases from $20\;\mathrm{m}{\mathrm{s}^{ - 1}}\mathrm{to}\;5\;\mathrm{m}{\mathrm{s}^{ - 1}}$ in a distance of 100 m. Force on the body is

A bullet hits and gets embedded in a solid block resting on a frictionless surface .In this process which one of the following is correct?

A body of mass $2 \mathrm{~kg}$ begins to move under the action of a time dependent force given by $\vec{F}=\left(6 t \hat{i}+6 t^2 \hat{j}\right) N$. The power developed by the force at the time $t$ is given by

Observer ${O_1}$ is in a lift going upwards and ${O_2}$ is on the ground. Both apply Newton’s law, and measure normal reaction on the body

When a ball is whirled in a circle and the string supporting the ball is released, the ball flies off tangentially. This is due to

The impulse on a particle due to a force acting on it during a given time interval is equal to the change in its

A large force is acting on a body for a short time. The impulsive imparted is equal to the change in

A car rounds an unbanked curve of radius 92 m without skidding at a speed of $26\;\mathrm{m}{\mathrm{s}^{ - 1}}$. The smallest possible coefficient of static friction between the tyres and the road is

Units of impulse is

Identify the correct statement.

A particle of mass $m$ is moving with a uniform velocity $v_1$. It is given an impulse such that its velocity becomes $v_2$. The impulse is equal to

A body of mass 0.05 kg is observed to fall with an acceleration of 9.5 $m{s^{ - 2}}$. The opposing force of
air on the body is $\left( {9.8\,\,m{s^{ - 2}}} \right)$

The x and y components of a force are 2 N and -3N. The force is

A cold soft drink is kept on the balance. When the cap is open, then the weight

An object is moving on a plane surface with uniform velocity $10 \mathrm{~ms}^{-1}$ in presence of a force $10 \mathrm{~N}$. The frictional force between the object and the surface is

Statement I: A cloth covers a table. Some dishes are kept on it. The cloth can be pulled out without dislodging the dishes from the table.
Statement II: For every action there is an equal and opposite reaction.

A good lubricant should be highly

A sphere of mass $m$ is rolling without sliding along positive $x$-axis on a rough horizontal surface of coefficient of friction $\mu$. It elastically collides with a wall and then returns. The correct statement of frictional force $(f)$ acting on the sphere is

Statement I: When the car accelerates horizontally along a straight road, the accelerating force is given by the push of the rear axile on the wheels.
Statement II: When the car accelerates, the rear axile rotates with a greater frequency.

A gun of mass 10 kg fires four bullet per second. The mass of each bullet is 20 g and the velocity of the bullet when it leaves the gun is $300\,m{s^{ - 1}}.$ The force required to hold the gun while firing is

Assertion(A): A glass ball is dropped on concrete floor can easily get broken compared, if it is dropped on wooden floor.

Reason(R): On concrete floor, glass ball will take less time to come to rest.

A block of mass 30 kg is pushed with a horizontal force of 100 N if the coefficient of static and kinetic friction are 0.5 and 0.4. The frictional force acting on the block is $\left( {g = 10\,m/{s^2}} \right)$

A block of mass 4 kg rests on a rough inclined plane making an angle of $45^\circ$ with the horizontal, if ${\mu _s} = 0.5$ The frictional force on the block is

A student attempts to pull himself up by tugging on his hair. He will not succeed

Statement-I: The work done in bringing a body down from the top to the base along a frictionless incline plane is the same as the work done in bringing it down the vertical side
Statement-II: The gravitational force on the body along the inclined plane is the same as that along the vertical side.