Question 8: What type of energy is stored in the spring of a watch? ANSWER When we wind the spring of a watch, we do work on it. This work appears as elastic potential energy of the spring. Mathematically, this work is equal to . Where ‘k’ is the spring constant. Therefore, Elastic potential energy in the spring = This potential energy then slowly converts to K-E and we see the needles of the watch moving round the clock.