DP Physics (last assessment 2024)

Question 20N.3.SL.TZ0.2a

Date	November 2020	Marks available	[Maximum mark: 1]	Reference code	20N.3.SL.TZ0.2a
Level	SL	Paper	3	Time zone	TZ0
Command term	State	Question number	a	Adapted from	N/A

[Maximum mark: 1]

20N.3.SL.TZ0.2a

A student studies the relationship between the centripetal force applied to an object undergoing circular motion and its period $T$ .

The object (mass $m$ ) is attached by a light inextensible string, through a tube, to a weight $W$ which hangs vertically. The string is free to move through the tube. A student swings the mass in a horizontal, circular path, adjusting the period $T$ of the motion until the radius $r$ is constant. The radius of the circle and the mass of the object are measured and remain constant for the entire experiment.

The student collects the measurements of $T$ five times, for weight $W$ . The weight is then doubled ( $2 W$ ) and the data collection repeated. Then it is repeated with $3 W$ and $4 W$ . The results are expected to support the relationship

$W = \frac{4 π^{2} m r}{T^{2}} .$

(a)

State why the experiment is repeated with different values of $W$ .

[1]

Markscheme

In order to draw a graph « of $W$ versus $\frac{1}{T^{2}}$ »
OR

to confirm proportionality between « $W$ and $T^{- 2}$ »

to confirm relationship between « $W$ and $T$ »

because W is the independent variable in the experiment ✓

OWTTE

Examiners report

Most candidates scored. Different wording was used to express the aim of confirming the relationship.