This video will break down step-by-step how to approach torque problems, and also explain the related concepts of lever arm/moment arm. Specifically, we'll be looking at problems where the object involved is held completely still, also known as "equilibrium," which is the most common problem type.

This is a tough topic, but the step-by-step process will help you break down and conquer even the toughest looking problem. Best of luck, and feel free to leave questions in the comments!

Timestamps:
0:00 Intro
1:30 Torque equation using Example
4:18 "Are torques forces, or not?"
5:28 How distance affects torque
7:25 How non-90-degree angles affect torque
11:18 Definition of "lever arm"/"moment arm"
11:39 Optional- alternate notation with F or r_perpendicular

16:51 Equilibrium and what it means for torque
18:53 *Where* does the weight force "pull"?

20:19 Torque balance example
26:44 Force at the rotation point? No torque! Why?

29:21 Step-by-step process
29:57 Step 1- Draw FBD with forces drawn *where* they push
31:41 Step 2- Draw an "X" at rotation center
32:28 Why is the X's position important?
32:38 Why you can sometimes put the X *anywhere*
33:20 Best places to put the X and why
36:30 Step 3- Decompose diagonal arrows (Only if using F_perpendicular notation)
37:06 Step 4- Clockwise torques = CCW torques
38:26 How to turn your diagram into this equation
41:48 Step 5- Count # equations vs. # unknowns
42:44 Step 6- Solve equations (usually)
43:16 Emergency step and when you might need it

45:02 Example where you need to use the emergency step
50:12 What to do if you're asked for the normal force/hinge force
51:04 Example- arm muscles and joints
56:33 Example- Masses balancing on a meterstick
1:02:15 Challenge example- Gate hanging off hinges and a wire

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