Throughout history, many designs of perpetual machines have been proposed. Class 9

Throughout history, many designs of perpetual machines have been proposed. Class 9

Question 1.

Throughout history, many designs of perpetual machines have been proposed but none actually work. Why do all real machines eventually slow down and stop? Explain in terms of work and energy. (Page 135) Class 9

Answer:

All real machines involve friction between moving parts. Friction converts mechanical energy into thermal energy (heat). According to the work-energy theorem and conservation of energy, the total energy remains constant - but friction continuously converts useful mechanical energy into thermal energy, which cannot be automatically recovered as mechanical energy. As a result, the mechanical energy of the machine decreases over time and it eventually slows down and stops. A perpetual motion machine would require zero energy loss, which is impossible in reality. Machines only transform energy; they cannot create it.

What if (Page 135)

Question 1.

What if it were possible to build a perpetual motion machine, which once started, could continue doing useful work forever, without any fuel or electricity? Class 9

Answer:

If such a machine were possible, it would violate the law of conservation of energy, which states that energy cannot be created or destroyed. It would mean energy is being produced without any input, which is not possible in real life. Hence, perpetual motion machines cannot exist.