Need help with spring constant experiment

Apr 2016
Hello everyone,

I am doing an experiment titled 'mass on a spiral spring' in order to find the value for the acceleration due to gravity in the first part of this experiment, I just measured the oscillation period of a spring as a suspended mass and plotted these results onto a graph to find the spring constant.

In the 2nd part of the experiment, I measured the ratio of the extension of the spring as a function of suspended mass to determine the value of g and plotted these results onto a graph, creating an e/m graph

My question to you, is to find the value of the acceleration of gravity, do you simply multiply the gradients of both graphs?


PHF Helper
Jun 2010
Morristown, NJ USA
In the first part of the experiment I assume you are plotting the period T as a function of varying masses, and in the second part you are plotting the extension as a function of mass, correct? If so, then think about the units of measurement here -- the slope of the first graph is seconds/Kg, and the slope of the second graph is meters/Kg. Multiply them together and you get m-s/Kg^2. That is not the same as the units for acceleration dues to gravity, which is m/s^2. So no - you can't simply multiply the two gradients. What I suggest is calculating the value for the spring constant from the first graph from T = (1/2) sqrt(m/k), and then use that value to calculate the value for g using data from the second part, from mg = (1/2) kx^2.