1. Torque Torque is an influence which tends to change the rotational motion of an object. One way to quantify a torque is Torque = Force applied x lever arm=F x r The lever arm is defined as the perpendicular distance from the axis of rotation to the line of action of the force.

2. Torque

4. Equilibrium

5. Torque Conditions for equilibrium 1.The sum of all the forces (net force) acting on an object is zero. 2. The sum of all the torques (net torque) acting on an object is zero.

6. Torque Mathematical notation

7. Torque By convention 1.Counterclockwise torque is positive 2.Clockwise torque is negative

8. Torque Consider a board balanced on its center with masses hanging on each side of the center.

9. Torque Use the following information. m 1 =1.0kg m 2 =1.0kg m 3 =3.0kg m board =2.0kg L 1 =2.0m L 2 =1.0m 1.What is the force exerted by the fulcrum? 2.What is L 3 ?

10. Torque Calculating the forces 1)There are no horizontal forces

11. Torque Because the board is balanced on its center its weight does not enter into the torque calculations.

12. Torque We can actually select any point as the axis of rotation, but it is convenient to use the point below which the board is supported.

13. Torque Calculating the torques

15. Torque Calculating the forces