Question

Question 6.7 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.

Chapter Work, Energy And Power Page 135

Answer 1

Hi--------------

(a) False
because in an elastic collision, the total energy and momentum of both the bodies, and not of each individual body, is conserved.

(b)false
here internal forces are balanced, they cause no work to be done on a body. only external forces that have the ability to do work. Hence, external forces are able to change the energy of a system.

(c)false
The work done in the motion of a body in a closed loop/close path is zero for a conservation force only.
In if force is nonconservative then workdone may not zero.

(d)true
In an inelastic collision, the final kinetic energy is always less than the initial kinetic energy of the system. This is because in such collisions, there is always a loss of energy in the form of heat, sound, etc.
and elastic collision ,energy is conserve,
hence, no change in initial and final kinetic energy .

hope it help u

Answer 2

Hey there !!!!!!!!!!

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Elastic collision is a collision in which both bodies together conserve energy and momentum.

So first statement is FALSE.

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Total energy of a system changes when some external forces act on the body. 

So given statement is FALSE.

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Conservative forces are forces which are path independent forces and work done remains the same in all cases for these forces. So work done in a closed loop is zero if force is conservative. It is not true for all forces.

Given statement is FALSE

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During an inelastic collision final kinetic energy decreases due to the collisions as a result it becomes lesser than initial kinetic energy.

So given statement is TRUE.

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HOPE THIS HELPED YOU....................