Answer:
(a)

(b)

Step-by-step explanation:
Let:
mass of father be,

mass of son be,

speed of son be,

initial speed of father be,

After speeding up, speed of father is

We know Kinetic Energy is given as
.....................................(1)
where:
m = mass
v = velocity
Hence, according to the initial condition the father is having kinetic energy half the kinetic energy of the son.



.................................................(2)
According to the final condition:



.....................................................(3)
(a)
From eq. 2 & 3





(b)
putting the above value in eq. (2)
