IB Physics SL A.2.24 Centripetal force

Get confident with circular-motion force questions by combining centripetal force with weight, tension, normal force, or friction.

Exam points

use a free-body diagram and set the resultant force equal to mv^2/r toward the centre
for bends, set maximum friction μmg equal to mv^2/r to decide the maximum safe speed
in loops, test whether normal force or tension stays above zero at the critical position

[Maximum number: 1]

This question is in two parts. Part 1 is about two children on a merry-go-round. Part 2 is about electric circuits.

Part 1 Two children on a merry-go-round
Aibhe and Euan are sitting on opposite sides of a merry-go-round, which is rotating at constant speed around a fixed centre. The diagram below shows the view from above.

Figure for Question A.2.24—Centripetal force question 1 — IB Physics SL

Aibhe is moving at speed $1.0 \mathrm{~ms}^{-1}$ relative to the ground.

Identify the force that is causing Aibhe to move in a circle.

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A.2.24—Centripetal force question 1