P Lab Torque

Define torque and state its formula.

Torque is a measure of how much a force causes an object to rotate.

τ=R⋅F⋅sin⁡(θ)

What condition must be satisfied for an object to be in rotational equilibrium?

For rotational equilibrium:

∑τclockwise=∑τcounter-clockwise

Why do we sometimes need to consider the mass of the bar in torque calculations?

If the bar has mass, its weight is distributed, and it exerts torque about the pivot. Ignoring it would lead to incorrect torque balance.

If a mass is placed farther from the pivot, how does that affect the torque?

Torque increases with distance. A force further from the pivot exerts more torque.

Explain what the following torque equation represents:

τbar​ = MgL²right/2L​​

It’s the torque caused by the right half of the bar’s mass, calculated as if all the mass is concentrated at its center of mass.

You place a 50 g mass 20 cm to the left of the pivot, and a 100 g mass 10 cm to the right. Are the torques balanced?

A uniform meter stick has a mass of 100 g. The pivot is placed at the 40 cm mark.
What is the torque due to the weight of the stick on the right side?

• m1=50 g at d1=20 cm

• m2=100 g at d2=10 cm (right)

• M=100 g stick, pivot at center

Determine if the torques are balanced.

Left torque:

τ=0.20⋅0.050⋅9.8=0.098Nm

Right torque from mass:

τ=0.10⋅0.100⋅9.8=0.098Nm

Stick is centered → symmetrical → no net torque.

✔ Balanced