A body of mass 5 kg is moving with a momentum of 10 kgms-1. A force of 0.2 N acts on it in the direction of motion of the body for 10s. the inerease in its kinetic energy is:
Correct answer: D. 4.4 J
- A. 2.8 J
- B. 3.2 J
- C. 3.8 J
- D. 4.4 J
Explanation
Option D is correct as the increase in kinetic energy is given by the following formula: ΔKE = 1/2mv2f - 1/2mv2i = 1/2 * 5 * 4.4^2 - 1/2 * 5 * 2^2 = 4.4 J where: ΔKE is the increase in kinetic energy m is the mass of the body = 5 kg v2f is the final velocity of the body = 2.4 m/s v2i is the initial velocity of the body = 2 m/s Therefore, the increase in kinetic energy of the body is 4.4 J.
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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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