ConceptConceptDocsDocuments

CAIE A-Level Physics 1 Physical Quantities & Units

Practise handling SI units, dimensions, estimates, uncertainties and scalar-vector distinctions in physical calculations.

Syllabus
2028–2030
Course
Physics 9702
Level
AS

Covered syllabus points

1.1 Physical quantities1.2 SI units1.3 Errors and uncertainties1.4 Scalars and vectors

1. Physical quantities and units question 1

[Maximum number: 11]

Question (a)

(a)

A property of a vector quantity, that is not a property of a scalar quantity, is direction. For example, velocity has direction but speed does not.

[ 4 ]

Question (i)

(i)

State two other scalar quantities and two other vector quantities.
scalar quantities: and vector quantities: and

[ 2 ]

Question (ii)

(ii)

State two properties that are possessed by both scalar and vector physical quantities.
1.
2.

[ 2 ]

Question (b)

(b)

A ship at sea is travelling with a velocity of 13 ms−113 \mathrm{~ms}^{-1} in a direction 35∘35^{\circ} east of north in still water, as shown in Fig. 1.1.

Fig. 1.1

Fig. 1.1

[ 7 ]

Question (i)

(i)

Determine the magnitudes of the components of the velocity of the ship in the north and the east directions.
north component of velocity = ms−1\mathrm{ms}^{-1}
east component of velocity = ms−1\mathrm{ms}^{-1}

[ 2 ]

Question (ii)

(ii)

The ship now experiences a tidal current. The water in the sea moves with a velocity of 2.7 ms−12.7 \mathrm{~ms}^{-1} to the west.

Calculate the resultant velocity component of the ship in the east direction.
resultant east component of velocity = ms−1\mathrm{ms}^{-1}

[ 1 ]

Question (iii)

(iii)

Use your answers in (b)(i) and (b)(ii) to determine the magnitude of the resultant velocity of the ship.
magnitude of resultant velocity = ms−1\mathrm{m} \mathrm{s}^{-1}

[ 2 ]

Question (iv)

(iv)

Use your answers in (b)(i) and (b)(ii) to determine the angle between north and the resultant velocity of the ship.
angle = ∘{ }^{\circ}

[ 2 ]

1. Physical quantities and units question 2

[Maximum number: 6]

Question (a)

(a)

A unit may be stated with a prefix that represents a power-of-ten multiple or submultiple.
Complete Table 1.1 to show the name and symbol of each prefix and the corresponding power-of-ten multiple or submultiple.

Table 1.1

Table 1.1

[ 2 ]

Question (b)

(b)

In the following list, underline all the units that are SI base units.

Table for Question (b) — CAIE A-Level Physics AS
[ 1 ]

Question (c)

(c)

The potential difference V between the two ends of a uniform metal wire is given by

V=4ρLIπd2V=\frac{4 \rho L I}{\pi d^{2}}

where d is the diameter of the wire,
I is the current in the wire,
L is the length of the wire,
and ρ\rho is the resistivity of the metal.
For a particular wire, the percentage uncertainties in the values of some of the above quantities are listed in Table 1.2.

Table 1.2

Table 1.2

The quantities listed in Table 1.2 have values that are used to calculate ρ\rho as 4.1×10−7Ω m4.1 \times 10^{-7} \Omega \mathrm{~m}. For this value of ρ\rho, calculate:

[ 3 ]

Question (i)

(i)

the percentage uncertainty

percentage uncertainty =2]
[ 2 ]

Question (ii)

(ii)

the absolute uncertainty.
absolute uncertainty = Ωm[1]\Omega \mathrm{m}[1]

[ 1 ]

1. Physical quantities and units question 3

[Maximum number: 1]

Which statement about errors in measurements is correct?

A

An accurate set of measurements always has a small random error.

B

A precise set of measurements always has a small systematic error.

C

A random error can be reduced by taking an average of several measurements.

D

A systematic error creates a random set of measurements spread out about the true value.

All question bank results loaded