Determine the magnitude of the torque

[deltas]

Homework Statement

A 25.0 N weight is held in the outstretched hand of a person with a shoulder-to-elbow length of 26.0 cm and an elbow-to-wrist length of 22.5 cm. The center of the weight is 7.5 cm from the person's wrist. A) Determine the magnitude of the torque about the elbow produced by the weight and B) Determine the magnitude of the torque about the shoulder produced by the weight.

http://educog.com/res/fsu/capalibrary/24equilibrium/Graphics/prob22a.gif​

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Homework Equations

Well, I can think of a few ways to solve for torque:

t = lF
t_net = I$$\alpha$$
t_net = I$$\alpha$$
(I = mr²)
(F = ma)

The Attempt at a Solution

Alright, well, for the first equation I knew that t = lF, where l is the lever arm distance and F is the force in Newtons.
l = 30.1 (a), 56.1(b)
F = ma
F = 2.55 x 9.81 = 25 (given)
t = 25 x 30.1 [56.1]
t = 752.5 NM [1403 NM]
Something is clearly not right here, help! I can tell I'm missing something basic, but I don't know what.

 

[ideasrule]

Check your units.

 

[deltas]

Centimeters? Was it centimeters the whole time?

 

[ideasrule]

It wasn't because you used Nm for the torque when it should be N*cm.

 

[deltas]

No, that's what I meant. I hadn't noticed that it was cm instead of m! Thank you!