IB Physics SL S Skills in Physics Questions

Practise IB Physics SL skills by handling units, uncertainties, graphs, instruments and measurements, then interpreting evidence in physical contexts.

Exam points

Choose instruments, variables and procedures, then record measurements with correct units, significant figures and uncertainties.
Apply algebra, trigonometry, graph methods, proportional reasoning and dimensional checks to physical calculations.
Design reproducible investigations with research questions, hypotheses, controls, variables, ranges, repeats and risk management.
Process data, assess trends and uncertainty, draw justified conclusions and evaluate errors, limitations and realistic improvements.

Covered syllabus points

S1.1 Experimental techniques S1.2 Technology S1.3 Mathematics S2.1 Exploring and designing S2.2 Collecting and processing data S2.3 Concluding and evaluating

[Maximum number: 2]

This question is about mobile phones.

The number of mobile phones has grown rapidly in recent years. Discuss environmental issues associated with this rapid increase.

[Maximum number: 5]

A group of students is investigating refraction in a semi-circular glass block.

Light from a ray box enters the curved side of the block. The light passes through the block and leaves, refracted, at P .

(a)

The students vary the position of the ray box to obtain data to determine the refractive index of the glass. They use a protractor to collect values for the angles of incidence $\theta_{i}$ and refraction $\theta_{r}$ at P and record them on a table.

[ 2 ]

(i)

One of their measurements is shown. State $\theta_{r}$ for this measurement.

[ 1 ]

$\theta_{r}=49$

Marking guidance:

Accept correct answer only

[1]

(ii)

Complete the table.

[ 1 ]

(b)

They plot a graph of the variation with the sine of $\theta_{i}$ of the sine of $\theta_{r}$ .
They add uncertainty bars for $\sin \theta_{r}$ for the first and last data point and draw the best-fit line.

[ 3 ]

(i)

Determine the gradient of the students' best-fit line.

[ 2 ]

use two points from the line that use more than half the line of best fit
gradient =1.5

Marking guidance:

Allow (implicit) use of the origin.

Look for $\Delta \mathrm{x} \geq 0.3$

[2]

(ii)

Draw on the students' graph the line of maximum gradient.

[ 1 ]

[Maximum number: 1]

A satellite powered by solar cells directed towards the Sun is in a polar orbit about the Earth.

The satellite is orbiting the Earth at a distance of 6600 km from the centre of the Earth.

Not all scientists agree that global warming is caused by the activities of man. Outline how scientists try to ensure agreement on a scientific issue.

[Maximum number: 6]

The density of a metal sphere is determined using a digital caliper and a mass balance.

The digital caliper is used to measure the diameter D of the sphere by placing the sphere in the jaws of the digital caliper. This reading is shown.

The sphere is then removed and another reading is taken immediately afterwards with the jaws closed.

(a)

Calculate D.

[ 1 ]

(b)

The manufacturer of the digital caliper states that the uncertainty in the device reading is $\pm 0.1 \mathrm{~mm}$ .

Calculate the percentage uncertainty in D.

[ 1 ]

(c)

State one way in which the procedure for the measurement of D can be improved using the same digital caliper.

[ 1 ]

(d)

The mass M of the sphere is $(54.0 \pm 0.2) \mathrm{g}$ .

The density of the sphere $\rho$ is calculated to be $11.3 \times 10^{3} \mathrm{~kg} \mathrm{~m}^{-3}$ , using $\rho=\frac{6 M}{\pi D^{3}}$ .

[ 3 ]

(i)

Calculate the percentage uncertainty in $\rho$ .

[ 2 ]

\% uncertainty in $M=\frac{0.2}{54.0} \times 100$ or 0.37 %

«Overall uncertainty $=0.37+(3 \times$ candidate answer to a(ii)) »
$\text { « }(0.37+3 \times 1.0)=\text { » } 3.4 \%$

Unrounded uncertainties lead to 3.2\% Allow 3\% or 4\% to 1 s.f.

Allow ECF from aii)

(ii)

State the value of $\rho$ , including the absolute uncertainty of $\rho$ .

[ 1 ]

« $0.034 \times 11.3 \times 10^{3}=0.4 \times 10^{3}$ »

$(11.3 \pm 0.4) \times 10^{3} \mathrm{~kg} \mathrm{~m}^{-3}$

Do not allow an absolute uncertainty expressed to more than 1 s.f. Allow ECF from ci)

Unit not required

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Covered syllabus points

Question 1

Question 2

Question (a)

Question (i)

Question (ii)

Question (b)

Question (i)

Question (ii)

Question 3

Question 4

Question (a)

Question (b)

Question (c)

Question (d)

Question (i)

Question (ii)