1. Torque and Angular Acceleration Torque =  = #Nm -a force acting at a distance away from a pivot -causes a twist -torque is vector -direction is often Clockwise (CW) Counterclockwise (CCW)  = F r or  = I 

2. Torque and Angular Acceleration Why is a door knob located as far as possible from the door hinge?

3. Torque and Angular Acceleration Why is a door knob located as far as possible from the door hinge? -You increase the “lever arm” Hinge Doorknob

4. Torque and Angular Acceleration Torque’s unit is Newton meters -Units of energy 1Nm = 1J -Never use Joules as a unit for torque.

5. Torque and Angular Acceleration Newton’s First Law (revisited) -An object at rest will remain at rest, an object rotating will remain rotating, unless acted upon by an unbalanced outside torque

6. Torque and Angular Acceleration Static Equilibrium Two Conditions -Forces must be balanced -Torques must be balanced

7. Torque and Angular Acceleration Static Equilibrium Scenario Two Forces are balanced N mg

8. Torque and Angular Acceleration Static Equilibrium Scenario Two Torques are balanced Mass 1= 50 grams Radius 1 = 10 cm Mass 2= 100 grams Radius 2 = 5 cm

9. H:\IP Sims\Rotational Dynamics\Net Torque Example.IP Torque and Angular Acceleration Let’s look at an example where torques are not balanced Click here…

10. Torque and Angular Acceleration Ladder Example (Ladder is at rest) Ground Wall

11. Torque and Angular Acceleration Ladder Example (Ladder is at rest) Ground Wall

12. Torque and Angular Acceleration Ladder Example (Ladder is at rest) Ground Wall F f1 F f2 N1N1 N2N2 mg

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