Laws of motion practice · Mixed difficulty

Assertion: A cricketer moves his hands forward to catch a ball so as to catch it easily without hurting.
Reason: He tries to decrease the distance travelled by the ball so that it hurts less.

A bullet of mass $0.04 {~kg}$ moving with a speed of $90 {~ms}^{-1}$ enters a having wooden block and is stopped after a distance of $60 {~cm}$. The average resistive force exerted by the block on the bullet is

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.

Three forces are acting on a body to make it in equilibrium, which set can not do it?

In a legend the hero-kid kicked a toy pig so that it is projected with a speed greater than that of its cry. If the weight of the toy pig is assumed to be 5 kg and the time of contact 0.01 s, the force with which the hero-kid kicked him was (Speed of cry = 330 m/s)

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)

Assertion: Impulsive force is large and acts for a short time.

Reason: Finite change in momentum should be produced by the force.

Body A is placed on frictionless wedge making an angle $\theta$ with the horizon. The horizontal acceleration towards left to be imparted to the wedge for the body A to freely fall vertically, is

A bullet of $10 \mathrm{g}$ leaves the barrel of gun with a velocity of $600 \,\mathrm{m} / \mathrm{s}$. If the barrel of gun is $50 \mathrm{cm}$ long and mass of gun is $3 \mathrm{kg}$, then value of impulse supplied to the gun will be:

A block of mass 10 kg starts sliding on a surface with an initial velocity of $9.8\,m{s^{ - 1}}$. The coefficient of friction between the surface and block is 0.5. The distance covered by the block before coming to rest is
[use $g = 9.8\,m{s^{ - 2}}$]

In a rocket, Fuel burns at the rate 2 kg/s. This fuel gets ejected from the rocket with a velocity of 80 km/s force exerted on the rocket is

The three central concepts in Newtonian mechanics are

For a body moving with relativistic speed, if the velocity is doubled then

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

A machine gun fires a bullet of mass 40 grams with a velocity $1200\,\,m{s^{ - 1}}$ . The man holding it can
exert a maximum force of 144 N on the gun. The number of bullets he can fire per second at the most is

A box is lying on an inclined plane what is the coefficient if static friction if the box starts sliding when an angle of inclination is 60°

Which of the following statements is not true

On the horizontal surface of a truck $\left( {\mu = 0.6} \right)$, a block of mass 1 kg is placed. If the truck is accelerating at the rate of $5m/se{c^2}$ then frictional force on the block will be

A body is sliding down an inclined plane forming an angle ${30^0}$ with the horizontal. If the coefficient of friction is 0.3. Then acceleration of body in $m/{S^2}$ is

Two trains $A$ and $B$ are running in the same direction on parallel rails such that $A$ is faster than $B$. Packets of equal weight are transferred between them. Which of the following statement is correct?

Assertion: On a roundabout, every portion of our body is subjected to an inward force.
Reason: Our body feels a push outward in the direction of impending motion.

A heavy uniform chain lies on horizontal table top. If the co-efficient of friction between the chain and the table surface is 0.5, the maximum percentage of the length of the chain that can hang over one edge of the table is

The distance covered by a body of mass $5 \mathrm{~g}$ having linear momentum $0.3 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ in $5 \mathrm{~s}$ is:

A body of mass $\mathrm{m}=3.513 \mathrm{~kg}$ is moving along the $\mathrm{x}$-axis with a speed of $5.00 \mathrm{~ms}^{-1}$. The magnitude of its momentum is recorded as

Which one of the following motions on a smooth plane surface does not involve force?

A body of mass $m$ is placed on a rough surface with coefficient of friction $(\mu)$ inclined at $\theta$. If the mass is in equilibrium, then

Newton’s Second law gives the measure of

Assertion: A body can be at rest even when it is under the action of any number of external forces.
Reason: Vector sum of all the external forces on a body may be zero.

The minimum force required to move a body up an inclined plane is three times the minimum force required to prevent it from sliding down the plane. If the coefficient of friction between the body and the inclined plane is $\frac{1}{{2\sqrt 3 }},$ the angle of the inclined plane is

A ball weighing $10 \mathrm{~g}$ hits a hard surface vertically with a speed of $5 \mathrm{~m} / \mathrm{s}$ and rebounds with the same speed. the ball remains in contact with the surface for $0.01 \mathrm{~s}$, then the average force exerted by the surface on the ball is :-