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CL 5 CH 2 Ws 5

This document contains 7 multiple choice and calculation problems involving combining uncertainties in experimental measurements. The problems involve calculating percentage uncertainties, expressing results to the appropriate number of significant figures, determining uncertainties in calculated values based on measured quantities, calculating average speeds and uncertainties, determining densities of materials from measurements of mass, length, and uncertainties, calculating wave speeds and uncertainties, and determining densities and uncertainties of materials based on measurements of diameter, length, mass and associated uncertainties.

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94 views2 pages

CL 5 CH 2 Ws 5

This document contains 7 multiple choice and calculation problems involving combining uncertainties in experimental measurements. The problems involve calculating percentage uncertainties, expressing results to the appropriate number of significant figures, determining uncertainties in calculated values based on measured quantities, calculating average speeds and uncertainties, determining densities of materials from measurements of mass, length, and uncertainties, calculating wave speeds and uncertainties, and determining densities and uncertainties of materials based on measurements of diameter, length, mass and associated uncertainties.

Uploaded by

trical27 trical
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Chapter 2 Combining Uncertainties WS

1. A thermometer can be read to an accuracy of ± 0.5 °C. This thermometer is used


to measure a
temperature rise from 40 °C to 100 °C.
What is the percentage uncertainty in the measurement of the temperature rise?

A 0.5 % B 0.8 % C 1.3 % D 1.7 %


2. A student makes measurements from which she calculates the speed of sound
as 327.66 m s–1.
She estimates that her result is accurate to ±3 %.
Which of the following gives her result expressed to the appropriate number of
significant figures?

A 327.7 m s–1 B 328 m s–1 C 330 m s–1 D 300 m s–1


3. The power loss P in a resistor is calculated using the formula P = V 2/R.
The uncertainty in the potential difference V is 3% and the uncertainty in the
resistance R is 2%.
What is the uncertainty in P?

A 4% B 7% C 8% D 11%
4 In an experiment, a radio-controlled car takes 2.50 ± 0.05s to travel 40.0 ± 0.1m.
What is the car’s average speed and the uncertainty in this value?

5. The density of the material of a rectangular block is determined by measuring


the mass and linear dimensions of the block. The table shows the results
obtained, together with their uncertainties.
mass = (25.0 ± 0.1)g
length = (5.00 ± 0.01)cm
breadth = (2.00 ± 0.01)cm
height = (1.00 ± 0.01)cm

The density is calculated to be 2.50gcm–3.


What is the uncertainty in this result?
6. The speed v of a transverse wave on a uniform string is given by the expression

where T is the tension in the string, l is its length and m is its mass.
An experiment is performed to determine the speed v of the wave. The
measurements are shown in Fig. 1.1.

Fig. 1.1
(a) (i) Use the data in Fig. 1.1 to calculate the speed v.

v = ................................................. m s 1 [2]

(ii) Use your answer in (b)(i) and the data in Fig. 1.1 to determine the value of v,
with its absolute uncertainty, to an appropriate number of significant figures.

v = ...................................... ± ...................................... m s 1 [3]

7. The volume V of the wire is given by the expression

The diameter, length and mass M are measured to determine the


density of the metal of the wire. The measured values are:
d = 0.38 ± 0.01 mm,
L = 25.0 ± 0.1 cm,
M = 0.225 ± 0.001 g.
Calculate the density of the metal, with its absolute uncertainty. Give your
answer to an appropriate number of significant figures.

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