IntermediateTopic 40 of 106Engineering Mechanics
Rolling motion
Rolling without slipping couples translation and rotation, v=ωr.
In depth
Rolling without slipping requires v=ωr at the contact point, which has zero velocity. Kinetic energy is ½mv²+½Iω². Rolling resistance arises from deformation, which is far smaller than sliding friction.
Key points
- Contact point is the instantaneous centre
- Acceleration down an incline a=g sinθ/(1+I/mr²)
- Static friction does no work
ExampleA solid sphere rolls down a slope at 5/7 g sinθ.
Rolling without slipping links translation and rotation, so it is central to wheel, ball and gear analysis.
What is Rolling motion?
Rolling without slipping couples translation and rotation, v=ωr.
Why is it important to understand rolling motion?
Rolling without slipping links translation and rotation, so it is central to wheel, ball and gear analysis.
Why does a rolling ball on a slope accelerate less than a sliding block?
Some of the energy goes into rotation, so less is available for linear motion, which reduces the translational acceleration.
What condition defines rolling without slipping?
The contact point has zero velocity, so the centre velocity equals angular speed times radius.
How is Rolling motion used in practice?
Typical applications include finding the speed of a car from wheel rotation, calculating the acceleration of a solid ball rolling down a ramp and checking the traction needed for a wheel to drive a vehicle without slipping.
What should I learn before Rolling motion?
Study "Gyroscopic effects" first (topic 39 of 106 in Engineering Mechanics). It covers the groundwork this topic builds on.
What are the key points of Rolling motion?
Contact point is the instantaneous centre. Acceleration down an incline a=g sinθ/(1+I/mr²). Static friction does no work.
Can you give an example of Rolling motion?
A solid sphere rolls down a slope at 5/7 g sinθ.
What comes after Rolling motion?
The next topic is "Circular motion and centripetal force", which builds directly on this one.
How difficult is Rolling motion?
It is classed as Intermediate in Engineering Mechanics (topic 40 of 106). It is an intermediate topic. Work through the beginner topics in Engineering Mechanics first.