A few days ago

help on physics?

1. What two factors are important in determining the amount of torque?

2.Doug wants to weigh his puppy, but does not have a scale available. Remembering the concept of torque from his physics class, he suspends a uniform 2m long rod from a rope in such a way that the rod is balanced. He places the puppy in a mesh bag and carefully hangs the bag from one end of the rod. He then places a 5lb (22.24N) bag of sugar in another bag and suspends it from the side of the rod opposite the puppy. He finds that the rod is balanced when the bag of sugar is a distance of 0.65m from the pivot. How much does the puppy weigh?

Top 2 Answers
A few days ago
Pro bono publico

Favorite Answer

General advice for solving physics problems: use dimensional analysis, that is look at the units. Check this link:


Units for torque are distance & Force – i.e. Ft-lbf, N-m, etc.

For your problem, the system will be in equilibrium when the FxD on both sides are equal…

Puppy Wt * 1m = 22.241N * 0.65m …. So:

Puppy Wt = ( 22.241N * 0.65m ) / 1 m = 14.457 N = 3.25 lbf


A few days ago
1. Torque=Moment arm x Force, the moment arm is the length of the lever in meters and the force should be measured in Newtons

2. Do the math yourself!