# What is the net torque about the axle?

#### a.a

1. The problem statement, all variables and given/known data

The 19.6 cm diameter disk rotates on an axle through its center. F1=22.8 N, F2=32.5 N, F3=32.5 N, F4=22.8 N, and d=4.60 cm. What is the net torque about the axle?

2. Relevant equations

Torque = F r sin (angle)
F = m g

3. The attempt at a solution

I found all the torques acting on the center, disregarded T1 because its sort of passing through the center and isnt really shown on the diagram.

T1 = 0
T2= (32.5)(0.196) = 6.37 Nm
T3= -(32.5)(sin 45)(0.046)= -1.057 Nm (counterclockwise)
T4= (22.8)(0.046)= -1.0488 (counterclockwise)

Tnet = 4.26 Nm

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#### Hootenanny

Staff Emeritus
Gold Member
Re: Torque

For a standard coordinate axis, counter-clockwise is usually taken as positive.

#### xboy

Re: Torque

Re-check the calculation for T2 .

#### Hootenanny

Staff Emeritus
Gold Member
Re: Torque

Re-check the calculation for T2 .
T2 looks fine to me (with the exception of the sign minus of course).

#### xboy

Re: Torque

Shouldn't he multiply the force with the radius (as opposed to the diameter)?

#### Hootenanny

Staff Emeritus
Gold Member
Re: Torque

Shouldn't he multiply the force with the radius (as opposed to the diameter)?
Of course he should. And I should pay more attention

#### a.a

Re: Torque

Of course he should. And I should pay more attention
wow.. thanks.. that was a dumb mistake...

"What is the net torque about the axle?"

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