# Need help with spring constant experiment

#### ambitious

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?

#### ChipB

PHF Helper
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.