Torque

Outline fun with seesaws two little people a big person and a little person two little people in different spots equation example

What Will Happen? Nothing

In this case the torques are equal The Bigger Torque Wins In this case the torques are equal so they balance out.

What Will Happen? Why?

The Bigger Torque Wins F A force is a push or a pull. The BIG FORCE creates a bigger torque than the little force. F

What Will Happen? Why?

Both forces are the same size. The Bigger Torque Wins Both forces are the same size. The BIG DISTANCE from the pivot point creates a bigger torque than the little distance. F F (pivot point = fulcrum)

What Will Happen?

The Bigger Torque will Win a little force with a BIG DISTANCE a BIG FORCE with a little distance F Which torque will be bigger?

Note: d is measured perpendicular to F Calculate Torque (T) T = F d distance force F Note: d is measured perpendicular to F d pivot point

What Will Happen? F = 200 lb d = 10 F = 50 lb d = 70 in

Use the Equation F = 200 lb d = 10 in T = 2000 in lb F = 50 lb

The Bigger Torque Wins T = 3500 in lb T = 2000 in lb

Which arm has more torque on it? 10 lbs Arm 2 F2 = Arm 1 F1 = 10 lbs d2 d1

Which arm has more torque on it? F1 = F2 d1 > d2 - so - T1 > T2 10 lbs Arm 2 F2 = Arm 1 F1 = 10 lbs d2 d1

Motors Provide Torque Torque from the motor makes the wheel spin. The maximum torque from a Vex motor is 6.5 in*lb.

Motor Example T = F d = 0.225 lb x 15 in d = 15 in motor pivot point F = 0.225 lb How much torque would the motor need to supply? T = F d = 0.225 lb x 15 in

Motor Example d = 15 in motor pivot point F = 0.225 lb How much torque would the motor need to supply? T = 3.375 in lb

Motor Example d = 15 in motor pivot point F = 0.225 lb The motor has more than enough torque to lift a tube, but it also has to lift the weight of the arm.

Can’t loosen a screw?

You need more TORQUE! Push harder (more force) -or- Use the long side of the allen wrench (longer distance)

Two ways to hold an Allen wrench Speed: fast Torque: low Speed: slow Torque: high

Use Torque to Tighten Screws Or your robot will end up like this!

Resources Inventor’s Guide: 3·10 http://www.education.rec.ri.cmu.edu/roboticscurriculum/vex_online/lessons/mechanics/torque/mechanics_torque.html Inventor’s Guide: 3·10