In elastic collision
both momentum and kinetic energies are conserved
both momentum and kinetic energies are not conserved
only energy is conserved
only mechanical energy is conserved
A.
both momentum and kinetic energies are conserved
In elastic collision both momentum and kinetic energies are conserved
A ball is released from the top of a tower. The ratio of work done by force of gravity in first, second and third second of the motion of the ball is
1 : 2 : 3
1 : 4 : 9
1 : 3 : 5
1 : 5 : 3
A body rolls down an inclined plane. If its kinetic energy of rotation is 40% of its kinetic energy of translation, then the body is
solid cylinder
solid sphere
disc
ring
A 10 kg object collides with stationary 5 kg object and after collision they stick together and move forward with velocity 4 ms-1. What is the velocity with which the 10 kg object hit the second one ?
4 ms-1
6 ms-1
10 ms-1
12 ms-1
When a force is applied on a moving body, its motion is retarded. Then the work done is
positive
negative
zero
positive and negative
An α-particle of mass m suffers one dimensional elastic collision with a nucleus of unknown mass. After the collision the α-particle is scattered directly backwards losing 75% of its kinetic energy. Then the mass of the nucleus is
m
2m
3m
An elastic ball is dropped from a height h and it rebounds many times from the floor. If the coefficient of restitution is e, the time interval between the second and the third impact, is
ev/g
e2v/g
An object of mass m is attached to light string which passess through a hollow tube. The object is set into rotation in a horizontal circle of radius, r1. If the string is pulled shortening the radius to r2, the ratio of new kinetic energy to the original kinetic energy is
Three point charges 1 C, 2C and 3C are placed at the corners of an equilateral triangle of side 1 m. The work done in bringing these charges to the vertices of a smaller similar triangle of side 0.5 m is
2.7 × 1010 J
9.9 × 1010 J
10.8 × 1010 J
5.4 × 1010 J