Rotational motion from "summary" of Physics Essentials For Dummies by Steven Holzner
Rotational motion is the type of motion involving objects that move around a fixed point in a circular path. It is a fundamental concept of physics and can be studied to better understand the behavior of objects in motion.- Rotational motion is the spinning or rotation of a body around its axis such as our planet rotating around its own axis or the spinning of an electric motor's rotor.
- A torque must be applied to an object for it to rotate, and when this happens, the object experiences angular acceleration-the change in speed of the spin of the object, which is called angular velocity.
- An important concept related to rotational motion is centripetal force–the force acting on a body traveling in a curved path at constant speed and directed toward the centre of the circle of motion.
- As an object moves with angular motion, any point on the object traces out a circular path known as angular displacement.
- It can also describe an object in free space that has angular momentum such as a satellite orbiting a larger body like Earth.
- Torques move objects into rotational motion, and the same forces against the object alter its movement; thus, conservation of angular momentum is established.
- If forces cause angular acceleration, there will be changes in angular momentum, and the calculation of both concepts requires vector calculus knowledge.
- The rotational equivalent to Newton's second law of motion is: Torque = Moment of Inertia times Angular Acceleration.
- Conservation of angular momentum states that unless an outside torque acts on a body, the angular momentum stays constant over time; so if the mass decreases then the angular velocity increases.
- This means that in order for an object to remain unchanged and balanced, the associated torques have to be equal in magnitude, but opposite in direction.
