DP Physics (first assessment 2025)

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Question 20N.1B.SL.TZ0.2b

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Date November 2020 Marks available [Maximum mark: 2] Reference code 20N.1B.SL.TZ0.2b
Level SL Paper 1B Time zone TZ0
Command term Predict Question number b Adapted from N/A
b.
[Maximum mark: 2]
20N.1B.SL.TZ0.2b
(b)

Predict from the equation whether the value of mr found experimentally will be larger, the same or smaller than the value of mr calculated directly.

[2]

Markscheme

ALTERNATIVE 1

W+friction=4π2mrT2

OR

centripetal force is larger «than W» / W is smaller «than centripetal» ✓

«so» experimental mr is smaller «than calculated value» ✓

 

ALTERNATIVE 2 (refers to graph)

reference to «friction force is» a systematic error «and does not affect gradient» ✓

«so» mr is the same ✓

 

MP2 awarded only with correct justification.
Candidates can gain zero, MP1 alone or full marks.

OWTTE

Examiners report

Most successful candidates chose to consider a single point then concluding that the calculated mr would be smaller than the real value as W < centripetal force, or even went into analysing the dependence of the frictional force with W. Many were able to deduce this. Some candidates thought that a graph would still have the same gradient (if friction was constant) and mentioned systematic error, so mr was not changed which was also accepted.

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