Question

when a mass of 2.5kg string is attached to a spring it stretches 42cm.
a) find the constant of the spring 'k'
b) how much force is required to stretch the spring 50cm?
c) how much energy is stored in the spring when stretched 0.35cm?

Answer 1

I guess it is hanging down on earth where g = 9.81 m/s^2 approximately

F = m g = k x

2.5 * 9.81 = k (.42)
solve for k

b) F = k (0.50)

c) U = (1/2) k x^2 = (1/2)(k)(0.35)^2