Hi there!
We can use the rotational equivalent of Newton's Second Law:

Στ = Net Torque (Nm)
I = Moment of inertia (kgm²)
α = Angular acceleration (rad/sec²)
We can plug in the given values to solve.

Answer:
40000÷40=1000 joules is required to work in 40 seconds
It increases as the number of protons and electrons in the shell increases
The change in momentum is 240 kgm/s
<u>Explanation:</u>
Given:
Force, F = 120N
Time, dt = 2 sec
Change in momentum, dP = ?
We know,

On substituting the value we get:

Therefore, change in momentum is 240 kgm/s