Read Chapter Sections 9.1, 9.2, and 9.3 in the textbook.
Activity 75.20 -
Watch this video on torque
- Torque is the result of applying a force on an object somewhere other than it's center of gravity.
- Torque causes an object to rotate.
- At its most basic level Torque is calculated by multiplying the Force applied times the Distance the force is from the object's pivot point.
- Torque = Force X Distance.
- Torque = (Force) (sin(angle)) (Distance)
- The angle referenced above is the angle between the applied force and the axis of the rotation of the object.
In the picture above the two people are sitting on a see saw.
Question: How far from the center does the person on the right need to sit to balance the see saw?
The person on the left is generating a force of (30 kg X 9.8 m/s/s) = 294 N . This force is creating a torque of (294N ) (2.0m) = 588Nm of counter clockwise torque of the left side of the see saw.
To put the see saw in balance (called rotational equilibrium) the counterclockwise torque must equal the clockwise torque. This is often written Tc = Tcc.
In this case the person sitting on the right side must generate 588Nm of clockwise torque to put the see saw in rotational equilibrium. Since they weigh (50kg x 9.8m/s/s) or 490N they must sit (588Nm/490N) or 1.2m from the center.
Complete this Introduction to Torque Google Classroom activity collecting the data fro the class demonstration.
Pick up a paper copy of these seminar problems. Look at the first problem and come up with an approach to solve it. Check your answer against the solution in the answer key. When you are done with the rest of the problems please check your answers here.
Pick up a paper copy of this document on concurrent forces. Make sure you understand the difference between concurrent and nonconcurrent forces.