State if each of the following statements is true or false. Give reasons for your answer.
(a) In an elastic collision of two bodies, the momentum and energy of each body is conserved.
(b) Total energy of a system is always conserved, no matter what internal and external forces on the body are present.
(c) Work done in the motion of a body over a closed loop is zero for every force in nature.
(d) In an inelastic collision, the final kinetic energy is always less than the initial kinetic energy of the system.
Answers
Answer:
(a) Decreases
A conservative force does a positive work on a body when it displaces the body in the direction of force. As a result, the body advances toward the centre of force. It decreases the separation between the two, thereby decreasing the potential energy of the body.
(b) Kinetic energy
The work done against the direction of friction reduces the velocity of a body. Hence, there is a loss of kinetic energy of the body.
(c) External force
Internal forces, irrespective of their direction, cannot produce any change in the total momentum of a body. Hence, the total momentum of a many- particle system is proportional to the external forces acting on the system.
(d) Total linear momentum
The total linear momentum always remains conserved whether it is an elastic collision or an inelastic collision.
Answer:
Explanation:
a) False.
-in an elastic collision , the total energy and momentum of both the bodies , and not of each individual body is conserved
b) False.
-Some energy is lost in heat, so it is not conserved.
c) False.
-It is true only for conservative forces. For non-conservative forces, work done over one cycle is not zero.
d) True.
-Some energy is lost in internal friction and heat.