Explanation:
Cell is a structural and fundamental unit mass of the body
The initial momentum of the system can be expressed as,

The final momentum of the system can be given as,

According to conservation of momentum,

Plug in the known expressions,

Initially, the second mass move towards the first mass therefore the initial speed of second mass will be taken as negative and the recoil velocity of first mass is also taken as negative.
Plug in the known values,

Thus, the final velocity of second mass is 2.99 m/s.
Power is defined as the rate at which the body is doing work:

Work is defined as displacement done by the force times that displacement:

We know that we need 62N to move the box, so when we apply this force along the path of 10m we have done:

of work.
Now we just divide that by 5s to get how much power is required:
micrometer is used to measure the diameter of a thin wire