Two bodies of masses 1kg and 2kg have the same momentum. The ratio of their K.E is:
Correct answer: C. 2:1
- A. 1:1
- B. 1:2
- C. 2:1
- D. 4:1
Explanation
Let the Kinetic energy of 1kg body be K.E1 and 2kg body be K.E2 K.E = 1/2 mv2 can also be written (m2v2)/2m P = mv m2v2 = p2 K.E = P2 / 2m K.E1 / K.E2 = (P2 / 2m1) / (P2 / 2m2) momentum is the same so it cancels out as well as the constant 2 K.E1 / K.E2 = (1 / m1) / (1 / m2) = (1 / 1) / (1 / 2) = 1/0.5 = 2/1 Hence, the ratio is 2 : 1
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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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