Ineed with this question i don’t understand

Explanation:

a) Sum of the forces on the seat in the radial direction:

∑F = ma

F = m v² / r

We know the mass m and radius r.  We need to find the velocity v.  We know it takes 10 s to make one revolution, so:

v = 2πr / t

v = 2π(10 m) / (10 s)

v = 2π m/s

Finding the force:

F = (50 kg) (2π m/s)² / (10 m)

F = 200 N

b) If the beam breaks, the seat's inertia keeps it moving tangent to the circle.

c) The instant that the beam breaks, the seat's velocity is the same as its tangential velocity:

v = 2π m/s = 6.28 m/s

d) (i) The work done by friction equals the change in kinetic energy:

W = ΔKE

W = ½ mv² − ½ mv₀²

W = ½ m (v² − v₀²)

W = ½ (50 kg) ((0 m/s)² − (5 m/s)²)

W = -625 J

(ii) Power = work / time

P = W / t

P = -625 J / 5 s

P = -125 W

the current is 0.6

voltage ÷ resistance = current

so 12 ÷ 20 = 0.6