# Moment Arm and Muscle Mechanics

- Author:
- Nicholas Larghi

This interaction allows students to use a slider to manipulate a simulated muscle at a simple hinge joint. The idea of this activity is to demonstrate the relationship between the moment arm and torque. The length of the moment arm changes throughout the motion of the muscle-joint interaction thus changing torque. This explains why it's hard to lift certain things from different angles.
Model calculations:
I did not apply actual force values in the interaction. The torque value here does not have units but is a mere representation in what the value would be. Torque was calculated from the cross products of two unit vectors multiplied by the sin of alpha.

At what angle is the torque the least?
At what angle is torque the greatest?
Can you explain the difference in torque at the two angles?