Question

What work a boy of mass 50kg will do in order to increase running speed from 9 km/h to 18 km/h

Answer 1

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$\huge\boxed{Hey there !}$

weight = 50 kg = 50 g

initial kinetic energy = 1/2m v^2 = 1/2* 50 kg* (9*5/18 m/sec)^2
= 62.5 joules

Final kinetic energy = 1/2*50 kg *(18 *5/18 m/sec)^2

=125 joules

Change in kinetic energy = work to be done

= 62.5 joules.

$<marquee> Hope it helps you !✌✌$

Answer 2

Answer:

468.75J

Explanation:

initial kinetic energy=1/2*50*(9*5/18)^2 = 25*(2.5)^2 = 25*6.25=156.25J

final kinetic energy = 1/2*50*(18*5/18)^2=625J

Work done = 625J-156.25J = 468.75J