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 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
B.
6 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