The staples inside a stapler are kept in place by a spring with a relaxed length of 0.110 m. If the spring constant is 49.0 N/m, how much elastic potential energy is stored in the spring when its length is 0.140 m?
Answer in units of J
Elastic potential energy is given by
Where k is the spring constant (49.0 N/m)
x is the displacement away from the rest length = Lf - Li = 0.030 m
EPE = 1/2 (49.0 N/m)(0.030 m)^2 = 0.0221 Nm or 0.0221 Joules.