IB Physics SL A.2.23 Circular Motion

Practise determining centripetal acceleration and its direction for discs, wheels, satellites and objects on strings.

Exam points

Calculate centripetal acceleration using speed and radius.
Identify the inward direction of circular acceleration and explain changing velocity.

[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)