This is a problem that seemed easy to me. I keep recalculating the answer, and I keep getting it wrong. I'm not sure if I'm approaching the problem incorrectly, or if i'm just making some small dumb mistake. Here's the question:(adsbygoogle = window.adsbygoogle || []).push({});

Big Ben (see the figure below), the Parliament Building tower clock in London, has hour and minute hands with lengths of 2.65 m and 4.45 m and masses of 61.0 kg and 101 kg, respectively. Calculate the total angular momentum of these hands about the center point. Treat the hands as long, thin uniform rods.

Ltot = Lmin + Lhour

L=I*W

Irod = .5*m*L^2

Wmin = 2pi/3600

Whour = 2pi/86400

Lmin = .5(101)4.45^2 * 2pi/3600 = 1.745

Lhour = .5(61)2.65^2 * 2pi/86400 = .0156

Ltot = 1.745 + .0156 = 1.76

1.76 is what I keep getting. Any thoughts, comments, help would be greatly appreciated. Thanks in advance.

-Brad

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Total Angular Momentum

**Physics Forums | Science Articles, Homework Help, Discussion**