a spring of force constant 1500NMis acted upon by a constant force of 75N.calculate the potential energy stored in the spring.
Stored PE = (1/2) k x^2
but x = F/k
so
PE = (1/2) k (F/k)^2 = (1/2) F^2 / k = (1/2) (75 N)^2 / 1500 N / meter
= 1.875 N meter = 1.875 Joules
or just say
average force * distance = 75/2 * 75/1500 = 1.875