Hooke’s Law

The formulas related to Hooke’s law are:

  • F = -k * x
  • k = -\dfrac{-F}{\lambda}
  • k =  \dfrac{(m*g)}{x}



A block is suspended from the ceiling and is 12 cm from the ceiling. The block has a mass of 3 kg. The spring has an unstretched length of 2 cm. Find the spring constant and the amount of elastic potential energy stored in the spring when the block is at this height.

Given: m = 3kg\quad g = 9.80 \quad  x = 10cm

Find: k = ? \quad PE_{SP}=?

A picture of the problem described

We can use Hooke’s Law to find the spring constant and potential energy.

k = [\frac{(3)(9.80)}{(0.10)}](\frac{1N}{(kgm/s^2) }= 294 N/m


So:\quad k=294 N/m \quad PE_{SP}=1.47 J