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Q5.7: NCERT Physics - Part 1 WORK, ENERGY AND POWER 5.7 Solution: State if each of the following statements is true or false.…
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.
Step-by-Step Verified Solution
**Answer:** (a) False (b) True (c) False (d) True
**Step-by-Step Explanation:**
(a) In an elastic collision, the total momentum and total kinetic energy of the system are conserved, but not necessarily for each body individually.
(b) The total energy of an isolated system is always conserved (law of conservation of energy).
(c) Work done over a closed loop is zero only for conservative forces. For non-conservative forces (like friction), it is not zero.
(d) In an inelastic collision, some kinetic energy is converted into other forms (heat, sound), so final KE < initial KE.
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