Good morning.
We have that:

, since we have rest in the inicial time.
The acceleration can be found with Newton's Law:

Now we put the acceleratin in the velocity equation:

We want the force, so, let's isolate
F:
The answer is m/s hope it helps
i do not know.....................................
Answer:
9000RPM
Explanation:
"Angular velocity" is directly related to kinetic energy, that is, the Kinetic energy equation would allow an approximation to the resolution investigated in the problem.
The equation for KE is given by:

Now, starting from there towards the <em>Angular equation of kinetic energy</em>, the moment of inertia (i) is used instead of mass (m), and angular velocity (w) instead of linear velocity (V)
That's how we get

calculating the inertia for a solid cylindrical disk, of
m = 400kg
r = 1.2 / 2 = 0.6m

We understand that the total kinetic energy is 3.2 * 10 ^ 7J, like this:



Thus,
943 rad / s ≈ 9000 rpm