Please help me int the following quesitons.

1.  

A man of mass 62kg

climbs up a stair case of 65 steps ,height of each step is 20cm,

time 12s.

his power=P=mgh/t

               =(62x10x65x20)/(100x12)

              =371.6W

 

2)The kinetic energy of an object moving with a velocity of 5m/s is 25J.

 

1/2 mx 5x5=25

m=2kg

 

 

What will be its kinetic energy when its velocity is made (i)two times (ii)three times?

 

as KE is proportional to square of vel, so :

 

its velocity is made (i)two times, KE will be 4 times.

 

  (ii)three times: then KE will be 9 times.