Laws of motion practice · Medium

$n$ balls each of mass impinge elastically (bounce back with same speed) in each second on a surface with velocity $u$. The average force experienced by the surface will be

A ball moves in a frictionless inclined table without slipping. The work done by the table surface on the ball is

Formula for true force is

There are different types of inertia called
I. Inertia of rest.
II. Inertia of motion.
III. Inertia of direction.
IV. Inertia of shape.
Choose the correct option.

A person sitting in an open car moving at constant velocity throws a ball vertically up into air. The ball falls

Which of the following is NOT a fundamental force in nature?

A car is moving with a uniform speed on a level road. Inside the car there is a balloon filled with helium and attached to a piece of string tied to the floor. The string is observed to be vertical. The car now takes a left turn maintaining the speed on the level road. The balloon in the car will (Here the car is supposed to be air tight)

Maximum speed of car for safe turning on horizontal road is

A stationary bomb explodes into two parts of masses 3kg and 1kg. The total KE of the two parts after explosion is 2400 J. The KE of smaller part is

Select the wrong statement(s) from the following.
I. Newton's laws of motion hold good for both inertial and non-inertial frames

II. During explosion, linear momentum is conserved
III. Force of friction is zero when no driving force is applied

Impulse equals

STATEMENT-1 : A block of mass $m$ starts moving on a rough horizontal surface with a velocity $v$. It stops due to friction between the block and the surface after moving through a certain distance. The surface is now tilted to an angle of $30^{\circ}$ with the horizontal and the same block is made to go up on the surface with the same initial velocity $v$. The decrease in the mechanical energy in the second situation is smaller than that in the first situation.

STATEMENT-2 : The coefficient of friction between the block and the surface decreases with the increase in the angle of inclination.

In an explosion a body breaks up into two pieces of unequal masses. In this

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

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?

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

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 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 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

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 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.