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Maths M2 Question plc help!

Hey can anyone help me with this, Its from this impossible m2 mock paper!!.

4) The resistance to the motion of a cyclist is modelled as kv^2 N , where k is a constant and v m/s is the speed of the cyclist. The total mass of the cyclist and his bicycle is 100kg. The cyclist freewheels down a slope inclined at an angle & (theta) to the horizontal, where sin& = 1/20 , at a constant speed of 3.5m/s.

a) Show that k=4


The cyclist ascends a slope inclined at an angle B to the horizontal, where sin B = 1/40 , at a constant speed of 2 m/s.

b) Find the rate at which the cyclist is working.

Thank u and gd luck!
Reply 1
1)
R = kv^2 = (3.5)^2.k
F = mgsin& - R = ma
Since v = const, a = 0
=> mgsin& - (3.5)^2.k = 0
=> k = 4 (g = 9.8m/s^2)

2)
v = const => a = 0
F = F(w) - (mgsinB + R) = 0
=> F(w) = mgsinB + R
(not sure if it is what the question asks)