# Homework Help: Torque experiment help

1. Oct 23, 2005

### Meteo

In this experiment, we had a half meterstick with a hole at one end. This was the pivot point.

Then about 4 cm from the pivot point was a scale which suspended the meterstick horizontally.

Then we had an unknown weight at the other end of the meterstick and we measured the force on the scale with different lever arm lengths of the unknown weight.

Then we graphed the torque exerted on the scale vs the lever arm length of the unknown weight.

The torque on the scale should be the torque of the meter stick + torque of the unknown weight.
the slope should = the weight of the unknown mass

the intercept should be the torque of the meterstick

Why is the slope = to the weight of the unknown mass and why is the intercept = to the torque of the meterstick

All I can do is derive the formula for the weight of the unknown mass in terms of the torque of the scale...
$$\tau_m+\tau_u=\tau_s$$

$$\tau_u=\tau_s-\tau_m$$

$$r_uw_u=\tau_s-\tau_m$$

$$w_u = \frac{\tau_s-\tau_m}{r_u}$$

but that doesnt help me at all...

Last edited: Oct 23, 2005