Download Rotational Kinetic Energy

Rotational Kinetic Energy
Section 10-10
Kinetic energy of an object
rotating about a fixed axis

 
K  mv

1
2
2
i i
1
2
mi R 
2
i
2
 m R 
K  I
1
2

1
2
i
2
2
i

2
Work
• For a constant force:
W  F d
• For a changing force:
W   F  dl
• For rotation:
W   F  dl   F Rd
W    d
Work-Energy Theorem
for body rotating about fixed axis
W  K  I  I
1
2
2
2
1
2
The work done in rotating a body through an
angle θ2 – θ1 is equal to the change in
rotational kinetic energy of the body.
2
1
Example 10-18 – Rotating Rod
A rod of mass M is pivoted on
a frictionless hinge at one
end. The rod is held at rest
horizontally and then
released. Determine the
angular velocity of the rod
when it reaches the vertical
position, and the speed of
the rod’s tip at this
moment.