1
Chapter 6: Circular Motion and
Gravitation
We briefly discussed motion at constant speed
in a circle.
Now that we know about forces, we can look
again at this.
We’ll also introduce Newton’s theory of
gravitation which often causes circular
motion.
Uniform Circular Motion - a reminder
An object moving at constant speed around a circular path has an acceleration
pointing radially inward
no acceleration component
parallel to the velocity?
- that would change the speed!
we found a formula
Uniform Circular Motion -
dynamics
So what happens if we remove the force? e.g. what if the string is cut?
vote:
1.
particle stops where it is
2.
particle moves at constant
speed along the radial
direction
3.
particle moves at constant
speed in the tangential
direction
Example 6.1 Model airplane on a string
Fly a propeller-driven model airplane on a 5.00m string in a horizontal circle. The airplane,
which has mass 0.500kg flies level and at constant speed and makes one revolution every 4.00
seconds. How hard must you pull on the string to keep the plane flying in a circle?
radial acceleration
speed

This
** preview**
has intentionally

**sections.**

*blurred***to view the full version.**

*Sign up*