A trolley runs from P to Q along a track. At Q its P.E is 50KJ less than at P. At P, the K.E of the trolley is 5KJ. Between P and Q, the work the trolley does against the friction is 10KJ. What is the kinetic energy of the trolley at Q?
Correct answer: C. 45 KJ
- A. 35 KJ
- B. 55 KJ
- C. 45 KJ
- D. 65 KJ
Explanation
At 'Q' P.E is 50KJ less than P.E at 'P'; at 'P' K.E=5KJ and workdone against friction is 10KJ. ΔU=-50KJ, friction removes10KJ. So K.E at 'Q'=K.E at 'P' +50-10= 5+50-10=45KJ
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Work transfers energy when a force causes displacement, while kinetic energy, gravitational potential energy and power describe motion, position and the rate of energy transfer. The work-energy theorem links net work with change in kinetic energy, and efficiency accounts for energy losses rather than treating them as energy destruction.
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