1. Contents
1. Rotational Motion
2. Rotational Inertia
3. Torque
4. Angular Momentum
5. Rotational Physics
6. Conservation of Angular Momentum

2. 1. Rotational Motion
▪ Circular motion and Rotational motion are very similar.
But,
Circular Motion - Curved path about an external axis(‘angular’).
Rotational Motion - Curved path about an internal axis.
▪ The word 'angular' is used to describe motion in a circular path.
▪ If you are moving in a curved path, you are passing through some
angle if you take the center of the path as the center of circle.
ex) The Earth moves in uniform circular motion about the sun.

3. 2. Rotational Inertia
▪ Rotational Inertia:
Objects with mass have inertia(Newton’s Laws)
- Tend to maintain their same state of motion
▪ The property of an object to resist changes in its rotational state of
motion is called rotational inertia

4. 2. Rotational Inertia
▪ In simpler terms, a rotating object tends to keep rotating
about its axis unless it is interfered with by an external
influence.
▪ Rotating objects tend to keep rotating, and non –rotating
objects tend to remain non-rotating.
▪ Depends on how the mass is distributed about the axis of
rotation.
▪ The pole has a large rotational inertia, helping the tight rope
walker to resist changes in his motion.
- prevent him from falling

5. 2. Rotational Inertia
▪ The rotational inertia of objects of different shapes can be
found using the objects mass and radius. Some examples are
shown below:

6. 2. Rotational Inertia
▪ Example:
Which of the following cylinders would you expect to win the race
down the ramp? You can assume the mass of each is the same.
The ring has greater rotational inertia, so it will take longer to get
rolling down the ramp. It will therefore lose. Its greater inertia,
however, will keep it rolling longer.