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NSWPhysicsQuick questions
Module 5: Advanced Mechanics
Quick questions on Uniform circular motion explained: HSC Physics Module 5
9short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is centripetal acceleration?Show answer
The acceleration points toward the centre of the circle:
What is centripetal force?Show answer
By Newton's second law, this acceleration requires a net inward force:
What is period, speed and angular velocity?Show answer
The period $T$ is the time for one full revolution. In one period the object travels the circumference $2\pi r$:
What is relationships between variables?Show answer
For a given object on a circular path:
What is calling centripetal force a separate force?Show answer
It is not. It is the net force directed toward the centre, supplied by friction, gravity, tension, or normal force. In a free-body diagram, you draw the real forces (gravity, normal, tension) and show that their resultant points to the centre.
What is confusing centripetal and centrifugal?Show answer
Centrifugal force is a fictitious force that appears only in a rotating reference frame. In HSC, work in the ground frame and use centripetal force only.
What is forgetting the direction?Show answer
Velocity is tangential to the circle. Acceleration and net force are radial, pointing toward the centre.
What is mixing units of angular velocity?Show answer
Use radians per second for $\omega$, not revolutions per second or degrees per second, unless you explicitly convert.
What is using diameter instead of radius?Show answer
$a_c = v^2 / r$, not $v^2 / d$.