Ferris wheel, centripetal force!

Question

A physics student decides to take a ride on an Ferris wheel, The wheel has a diameter of 12 m and spins at a constant rate making three complete revolutions per minute.

(i) Determine the speed of the student

Circumference = π*12m = 12πm

Three revolutions = 3*12πm = 36πm

speed = 36πm/60s = 1.88m/s

(ii) the magnitude of acceleration of the student. If the acceleration of the student is zero, state so explicitly.

v²/r = 12m/2 = 6m (1.88 m/s² /6m) = 0.589 m/s²

(iii) The physics student, wishing to test Newton's law of motion, sits on a bathroom scale as the Ferris wheel moves through a complete circle. At the lowest point in the motion, the scale reads 800 N. Determine mass of the student in kg.

*****I DON'T KNOW HOW TO SOLVE FOR THE THIRD PART******

Answer 1

To find the mass, we can first write an expression for the net force acting on the student. An equation for net force consists of the sum of the gravitational force (downward) and the upward force from the scale.

∑F = F_scale - mg

We can replace ∑F with ma (mass*acceleration) according to Newton's second law. Then, we can solve the expression for mass given the acceleration that was solved for in the previous part and the value of g (9.8 m/s²).

ma = F_scale - mg