IB Physics SL A.2.23 Centripetal acceleration

Practise calculating centripetal acceleration from speed, radius or angular speed, and linking its direction to motion in a circle.

Exam points

use a = v^2/r or a = rω^2 to calculate acceleration from rotation rate, period or linear speed
interpret rotating-disk or wheel points by comparing acceleration using distance from the centre
show the acceleration direction on a diagram by drawing it towards the centre of the circular path

[Maximum number: 3]

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.2.23—Centripetal acceleration question 1 — IB Physics SL

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

(a)

Draw an arrow on the diagram on page 22 to show the direction in which Aibhe is accelerating.

[ 1 ]

(b)

Aibhe moves so that she is sitting at a distance of 0.75 m from the centre of the merry-go-round, as shown below.

Euan pushes the merry-go-round so that he is again moving at $1.0 \mathrm{~ms}^{-1}$ relative to the ground.

[ 2 ]

(i)

Calculate the magnitude of Aibhe's acceleration.
Part 2 Electric circuits

[ 2 ]

$\quad a\left(=\frac{v^{2}}{r}\right)=\frac{0.5^{2}}{0.75}$ ;
$a=0.33\left(\mathrm{~ms}^{-2}\right)$ ;

Marking guidance:

Allow ECF from (d)(i).
Award [2] for a bald correct answer.

Part 2 Electric circuits

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A.2.23—Centripetal acceleration question 1

Question (a)

Question (b)

Question (i)