Assertion : Kinetic energy of a body becomes four times, when its linear momentum is doubled.
Reason : This is because, K.E. = p2 /2m.
Important Questions on Centre of Mass, Momentum and Collisions
Reason: Product of mass of one particle and its distance from the centre of mass is numerically equal to the product of the mass of other particle and its distance from the centre of mass.
Reason: Centre of mass of a body is a point, where the whole mass of the body is supposed to be concentrated.
Assertion: The position of centre of mass of a body does not depend upon the shape and size of the body.
Reason: Centre of mass of a body always lies at the centre of the body.
Assertion: Location of centre of mass is independent of the reference frame.
Reason: Centre of mass is the same as centre of gravity.
Assertion: The centre of mass of electron and proton, when released moves faster towards proton.
Reason: Proton is heavier than electrons.
Assertion: Kinetic energy is conserved in both, perfectly elastic and inelastic collisions.
Reason: Because both types of collisions are identical.
Reason: In firing, momentum is conserved.
Assertion: In an elastic collision of two billiards balls, the kinetic energy is not conserved during the short interval of time of collision between the balls.
Reason: Energy spent against friction does not follow the law of conservation of mechanical energy.
