What is the net torque about the axle?

In summary, the conversation discusses the calculation of net torque on a rotating disk with given forces and distances. After finding the torques acting on the center, the equation for torque is used to calculate the net torque. A mistake in the calculation of T2 is pointed out and corrected, resulting in the correct answer.
  • #1
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Homework Statement



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?

Homework Equations



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

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 isn't 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

This isn't the right answer, can someone please help and explain where I am going wrong..
 

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  • #2


For a standard coordinate axis, counter-clockwise is usually taken as positive.
 
  • #3


Re-check the calculation for T2 .
 
  • #4


xboy said:
Re-check the calculation for T2 .
T2 looks fine to me (with the exception of the sign minus of course).
 
  • #5


Shouldn't he multiply the force with the radius (as opposed to the diameter)?
 
  • #6


xboy said:
Shouldn't he multiply the force with the radius (as opposed to the diameter)?
Of course he should. And I should pay more attention :redface:
 
  • #7


Hootenanny said:
Of course he should. And I should pay more attention :redface:

wow.. thanks.. that was a dumb mistake...
 

Related to What is the net torque about the axle?

What is the net torque about the axle?

The net torque about the axle refers to the total amount of rotational force acting on an object around its axis of rotation. It takes into account the magnitude and direction of individual torques acting on the object.

How is net torque about the axle calculated?

To calculate the net torque about the axle, you need to first determine the individual torques acting on the object. Then, you can use the formula net torque = (force * distance) + (force * distance) + ... to calculate the sum of all the torques. This will give you the net torque about the axle.

What factors affect the net torque about the axle?

The net torque about the axle is affected by the magnitude and direction of individual torques, as well as the distance from the axis of rotation at which they act. The angle at which the forces act can also affect the net torque.

Can the net torque about the axle be negative?

Yes, the net torque about the axle can be negative. This means that the rotational forces acting on an object are in opposite directions, causing a net torque in the opposite direction of the object's rotation.

Why is understanding net torque about the axle important?

Understanding net torque about the axle is important in various fields of science and engineering, such as mechanics, physics, and robotics. It helps us understand how objects rotate and how to manipulate forces to achieve desired movements or stability.

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