Collisions

IMPORTANT

Collisions: Overview

This topic covers concepts, such as Head-on Inelastic Collision, Perfectly Inelastic Collision, Head-on and Oblique Collisions, Collisions, Expressions of Velocities after Elastic Collision, and Linear Momentum and Collisions.

Important Questions on Collisions

MEDIUM
IMPORTANT

A small block of mass M moves on a frictionless surface of an inclined plane, as shown in the figure. The angle of the incline suddenly changes from 60 to 30at point B. The block is initially at rest at A. Assume that collisions between the block and incline are totally inelastic. g=10 m/s2Question Image

If the collision between the block and the incline is completely elastic, then the vertical (upward) component of the velocity of the block at point B, immediately after it strikes the second incline is:

MEDIUM
IMPORTANT

A block of mass 0.50 kg is moving with a speed of 2.00 m s-1 on a smooth surface. It strikes another mass of 1.00 kg and then they move together as a single body. The energy loss during the collision is:

MEDIUM
IMPORTANT

Two small particles of equal masses start moving in opposite directions from a point A in a horizontal circular orbit. Their tangential velocities are v and  2 v, respectively, as shown in the figure. Between collisions, the particles move with constant speeds. After making how many collisions, other than that at A, these two particles will again reach the point A?

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MEDIUM
IMPORTANT

A smooth sphere A is moving on a frictionless horizontal plane with angular speed ω and centre-of- mass velocity v. It collides elastically and head-on with an identical sphere B at rest. Neglect friction everywhere. After collision, their angular speeds are ωA and ωB respectively. Then:

MEDIUM
IMPORTANT

Consider a rubber ball freely falling from a high height  h = 4.9 m on to a horizontal elastic plate. Assume that the duration of collision is negligible and the collision with the plate is totally elastic. Then the velocity as a function of time and the height as a function of time will be:

HARD
IMPORTANT

Two particles of masses m1 and m2, in projectile motions, have velocities v1<v2 respectively at t=0. They collide at time t0. The velocities become v1 and v2 at time 2t0 while moving in air. The value of m1v1+m2v2m1v1+m2v2 is

HARD
IMPORTANT

A point mass of 1 kg collides elastically with a stationary point mass of 5 kg. After their collision, the 1 kg mass reverses its direction and moves with a speed of 2 m s-1. Which of the following statements is correct for a system of these two masses?

EASY
IMPORTANT

A body of mass m is moving with speed v makes a one-dimensional collision with a stationary body of the same mass on a horizontal table. They are in contact for a very small interval of time Δt. The contact force between them varies as shown in the graph. (Neglect friction). The coefficient of restitution for the collision will be

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EASY
IMPORTANT

A charged particle moves towards another charged particle. Under what conditions the total momentum and the total energy of the system conserved?

EASY
IMPORTANT

Which is conserved in inelastic collision? Total energy (or) Kinetic energy?

HARD
IMPORTANT

A mass M moving with a certain speed V collides elastically with another stationary mass m. After the collision, the masses M and m move with speeds V' and v respectively. All motion is in one dimension. Then,

MEDIUM
IMPORTANT

Two point objects A and B each of mass 3 g and initially at rest are connected by massless threads as shown in the figure. A constant force 2 N acts on the system at point P along OP. After the point O has moved a distance 20 cm in the direction of force, the two objects collide and stick together. The displacement and velocity of the centre of mass of the system immediately after collision are respectively

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MEDIUM
IMPORTANT

A ball of mass m moving at speed u makes a head-on collision with an identical ball at rest. The kinetic energy of the balls after the collision is three-fourth of the original. The coefficient of restitution (e) is

EASY
IMPORTANT

Two particles having position vectors r 1 = 3 i ^ +5 j ^ m and r 2 = 5 i ^ 3 j ^ m at t=0 are moving with velocities v1=4i^+3j^ m s-1 and v 2 = a i ^ +7 j ^ m s-1. For what value of 'a' they collide at =2 sec

MEDIUM
IMPORTANT

Block A is hanging from a vertical spring and is at rest. Block B strikes the block A with velocity v and sticks to it. Then the value of v for which the spring just attains natural length is :-

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MEDIUM
IMPORTANT

A neutron moving with a speed 'v' makes a head on collision with a stationary hydrogen atom in the ground state. The minimum kinetic energy of the neutron for which inelastic collision will take place in eV (closest to nearest integer) is:

HARD
IMPORTANT

A rod AB of mass M and length L is lying on a horizontal frictionless surface. A particle of mass m travelling along the surface hits the end A of the rod with a velocity v0 in a direction perpendicular to AB. The collision is completely elastic. After the collision the particle comes to rest.

A point P on the rod is at rest immediately after the collision. Find the distance AP.

HARD
IMPORTANT

For next two question please follow same

A rod AB of mass M and length L is lying on a horizontal frictionless surface. A particle of mass m travelling along the surface hits the end A of the rod with a velocity v0 in a direction perpendicular to AB. The collision is completely elastic. After the collision the particle comes to rest.

Find the ratio  m M .

HARD
IMPORTANT

For next two question please follow the same

Electrostatic force on a charged particle is given by F = q E . If q is positive F E  and if q negative F E

In the figure mA = mB = 1 kg. Block A is neutral while qB = - 1C. Sizes of A and B are negligible. B is released from rest at a distance 1.8 m from A. Initially  spring is neither compressed nor elongated.

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If collision between A and B is perfectly inelastic, what is velocity of combined mass just after collision?

MEDIUM
IMPORTANT

Particle A moves with speed 10 m s-1 in a frictionless circular fixed horizontal pipe of radius 5 m and strikes with B of double mass that of  A. Coefficient of restitution is known to be 1/2 and particle A starts its journey at t=0. What will be the time at which second collision occurs?

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