# How do you calculate the energy required via torque when...

1. May 13, 2015

### warfreak131

Let's say you have a lever arm connected to a load at the end. But the load is attached to a hinge, so no matter where the lever arm is, the load is always pointing down. I know that Energy = [integral] tau d_phi, but does that only work if the angle b/w arm and load is constant?

What if the angle between the arm and the load, theta, is changing throughout the rotation, phi?

#### Attached Files:

• ###### torque.png
File size:
11.4 KB
Views:
72
2. May 13, 2015

### eifphysics

If the angle θ is not constant. We can just take the integral ∫τ·dφ, τ = Frsinθ, with F and θ in terms of φ. If both F and θ are constant than we do not need an integral. I think you might have some misunderstanding about the concept of integral. Also, what do you mean by "load"?

3. May 13, 2015

### warfreak131

The "load" is just my way of saying the force. I understand the integral, I just wasn't sure if it was as easy as dropping in the FrSin[x] into the integral, but I guess it is. Thank you.

4. May 13, 2015

### eifphysics

Another Suggestion. If you do not know Latex, you can search for an online math input platform to enter mathematical expressions.