Torque

Definition

The tendency of a force applied to an

object to cause rotation about an axis.

F

r

F

r

Torque is a product of the moment arm (r) and the force F

Cross Product

= r x F

i x i = 0 i x j = k i x k = -j

j x i = -k j x j = 0 j x k = i

k x i = j k x j = -i k x k = 0

Right Hand Rule

•Draw vectors so that tails coincide

•Point fingers of right hand in direction of first vector (r)

•Bend Fingers in direction of second vector (F)

•Thumb points in direction of cross product

= r F sin

Another equation

F

r

I

Rotational “Second Law”

m = 10 kgr = 1.5 mF = 100 N= 32o

= ½ MR2

= ?