Question

physics numericals,

how fast should a body of mass 40 kg run so that its kinetic energy be 720 J .​

Answer 1

Explanation:

Given, mass m=40kg,K.E=320J,v=?

K.E=

2

1

mv

2

320=

2

1

×40v

2

v

2

=

40

640

=16

v=4m/s

So, the girl of 40 kg should run at 4m/s so that her kinetic energy is 320J.

Answer 2

Answer:

Given, mass of the man, m=60kg

Kinetic energy of the man, E k=750J

If v is the velocity of the man, then

Ek =1/2 mv²

or v= √2Ek/m=√2×750 /60=5m/s