Question

How fast should a man weighing 800N run so that his kinetic energy
is 560J?

Answer 1

W=600N,g=10ms

−2

, kinetic energy =750J,v=?

W=mg

∴ 600=m×10

or, m=60kg

Now, kinetic energy=

2

1

mv

2

or, 750=

2

1

×60×v

2

or, v

2

=

60

2×750

=25

or, v=

25

=5ms

−1