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A body of mass m = 10 –2 kg is moving in a medium and experiences a frictional force F = –kv 2 . Its initial speed is v 0 = 10 ms –1 . If, after 10 s, its energy is 2 0 mv 8 1 , the value of k will be-

1. 10 –3 kg m –1
2. 10 –3 kg s –1
3. 10 –4 kg m –1
4. 10 –1 kg m –1 s –1

Correct answer: 10 –4 kg m –1

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