Question

Recall that in the equilibrium position, the upward force of the spring balances the force of gravity on the weight. Use this concept, along with the variable mass value, the ruler, and the moveable line, to estimate the spring constant k of the spring. Set the damping to "Lots" so that the mass will come to rest quickly after being changed, and make sure the gravity is set to "Earth." Finally, set the spring constant to "Small." Estimate the spring constant several times (using different values of mass) and average together for the most accurate calculation.

Answer 1

Recall that in the equilibrium position, the upward force of the spring balances the force of gravity on the weight is given below.

Explanation:

Measure unstretched length of spring, L.  E.g. L = 0.60m.

Set mass to a convenient value (e.g. m = 0.5kg).

Hang mass.

Measure new spring length, L'. E.g. L' = 0.70m.

Calculate extension: e = L' - L = 0.70 – 0.60 = 0.10m

Use mg = ke (in equilibrium weight = tension)

k = mg/e

Don't know what value you are using for example.  Suppose it is 10N/kg (same thing as 10m/s²).

k = 0.5*10/0.10 = 50 N/m

Repeat for a few different masses.  (L always stays the same.)

Take the average of your k values.