Question

a person of mass 60 kg is running with the velocity of 20 m/s. what is his power if he competes the race in 30 seconds.
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Answer 1

Explanation:

ANSWER

In this their is no external force is acting so center of mass of the system will not move so

M

1

v

1

+M

2

v

2

=0 .... eq1

M

1

=60kg,M

2

=20kg,v

1

=3ms

−1

60×3+20×v

2

=0

⇒v

2

=−9ms

−1

negative sign indicate that trolley move opposite to the direction of the man velocity.

Energy produce by the man is used to give velocity to himself and the trolley

E=

2

1

M

1

v

1

2

+

2

1

M

2

v

2

2

⇒E=

2

1

×60×3

2

+

2

1

×20×9

2

=1.08KJ

Hence the velocity of the trolley is 9ms

−1

and energy produce by the man is 1.08KJ