Centripetal forceEdexcel A-Level Physics: Flashcards

What these 14 flashcards ask

Why does an object moving in a circle at constant speed accelerate?
In which direction does the resultant force act on an object in circular motion?
Why does the centripetal force do no work?
Give three expressions for centripetal force.
How are v and ω related?
How is ω related to the period and frequency?
What happens to the force needed if the speed doubles at constant radius?
What happens to the force needed if the radius doubles at constant angular speed?
What provides the centripetal force for a car on a flat bend?
What provides the centripetal force for a conker whirled on a string?
Is centrifugal force a real force acting on a body in circular motion?
State the contact force at the top of a hump-back bridge.
State the contact force at the bottom of a dip.
At what speed does a car lose contact at the top of a bridge of radius r?

Exam questions on Centripetal force

A puck of mass 0.25 kg is attached to a light string, the other end of which is fixed to a smooth horizontal table. The puck moves in a horizontal circle of radius 0.80 m at a constant speed of 4.0 m s⁻¹.
Calculate the tension in the string.2 marks
A car of mass 1200 kg travels at a constant speed of 14 m s⁻¹ round a flat, circular roundabout of radius 25 m. The maximum sideways frictional force that the tyres can exert on the road surface is 8.0 kN.
Deduce whether the car can travel round the roundabout at 14 m s⁻¹ without skidding.2 marks
A fairground 'rotor' ride is a vertical cylinder of radius 2.5 m that rotates about its vertical axis at a constant angular speed of 3.0 rad s⁻¹. A rider of mass 60 kg stands against the inside wall of the cylinder. Once the cylinder is rotating at full speed the floor is lowered, and the rider stays in contact with the wall without sliding down.
Calculate the speed of the rider and the resultant force on the rider.3 marks

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).