Laws of motion practice · Medium

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 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.

A 60 kg man stands on a spring scale in the lift. At some instant he finds, scale reading has changed from 60 kg to 50 kg for a while and then comes back to the original mark. What should we conclude

A body of 5 kg is moving with a velocity of 20m/s. If a force of 100N is applied on it for 10s in the same direction as its velocity, what will now be the velocity of the body

For a system to follow the law of conservation of linear momentum during a collision , the condition is
Total external force acting on the system is zero.
Total external force acting on the system finite and time of collision is negligible.
Total internal force acting on the system is zero.

A bird weighs 2 kg and is inside a closed cage of 1 kg. If it starts flying, then what is the weight of the bird and cage assembly

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.

Physical independence of force is a consequence of

A particle is moving in a circular path with a constant speed v. If $\theta$ is the angular displacement, then starting from $\mathrm{\theta } = 0^\circ$, the maximum and maximum changes in the momentum will occur, when value of θ is respectively

A body is moving on a horizontal surface. The force of friction acting between them is called

If the resultant of all the external forces acting on a system of particles is zero, then form an inertial frame, one can surely say that

A uniform metre scale balances at the 40-cm mark when weights of 10g and 20g are suspended from the 10-cm and 20-cm marks respectively. The weight of the metre scale is

(A): A solid sphere and hollow sphere when released from the top of a smooth and fixed inclined plane, reach the ground simultaneously.
(R): Acceleration while sliding on a smooth inclined plane is independent of mass and dimension of the body.

A block of mass $m$ is placed on a rough horizontal surface. If $100 \mathrm{~N}$ of force is applied on it and it moves $10 \mathrm{~m}$. Then find the work done by friction on the block.

particle moves in the X-Y plane under the influence of a force such that its linear momentum is $p\left( t \right) = A[\hat i\cos \left( {kt} \right) - \hat j\sin \left( {kt} \right)]$ where A and k are constant. The angle between the force and the momentum is

A ball is moving to and fro about the lowest point A of a smooth hemispherical bowl. If it is able to rise up to a height of 20 cm on either side of A, its speed at A must be $(Take\;g = 10\;m/{s^2},\;$ massof the body 5 g)

Assertion: Frictional forces are conservating forces.
Reason: Potential energy can be associated with frictional forces.

Assertion: When a person walks on a rough surface, the frictional force exerted by the surface on the person is opposite to the direction of the tendency of motion of his legs.
Reason: If a body moves with constant velocity, it implies that it is moving along a straight line and there is no acceleration.

In which of the following cases forces may not be required to keep the

In relativity which is constant between two frames of reference

A disc rotates about its axis of symmetry in a horizontal plane at a steady rate of 3.5 revolutions per second. A coin placed at a distance of 1.25 cm from the axis of rotation remains at rest on the disc. The coefficient of friction between the coin and the disc is $\left( {g = 10m/{s^2}} \right)$

A block compartment containing gas is moving with some acceleration in horizontal direction. Neglect effect of gravity. Then the pressure in the compartment is

A block of mass 1 kg lies on a horizontal surface in a truck, the coefficient of static friction between the block and the surface is 0.6. The force of friction on the block if the acceleration of the truck is $5\,m{s^{ - 2}}$ is: $\left( {g = 10m/{s^2}} \right)$

Assertion : On a rainy day, it is difficult to drive a car or bus at high speed.
Reason : The value of coefficient of friction is lowered due
to wetting of the surface.

Statement-I: The velocity of a body at the bottom of an incline plane of given height is more when it slides down the plane, compared to, when it rolling down the same plane.
Statement-II: In rolling down a body acquires both, kinetic energy of translation and rotation.

If a person with a spring balance and a body hanging from it goes up and up in an aeroplane, then the reading of the weight of the body as indicated by the spring balance will

What should be the coefficient of friction between the tyres and the road, when a car travelling at 60 $\mathrm{km\;}{\mathrm{h}^{ - 1}}$ makes a level turn of radius 40 m?

Frictional force that opposes relative motion between surfaces in contact is called ...X... and denoted by ...Y.... Here, X and Y refer to

Five forces inclined at an angle of $72^{\circ}$ w.r.t. each other act on a particle of mass $m$ placed at the origin. Four forces are of magnitude $F_1$ and one has a magnitude $F_2$. Find the resultant acceleration of the particle.