8/14/2019 Paper 3 Jun 1999 Physics

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Answer guide for O Level Physics (5054/3) Paper 3 Practical Test June 1999

Page 1 of 2 UCLES 2002

1(a) Mass of 20 spheres = m

S

- m

P

Mass of one sphere = (Mass of 20 spheres)/20 e.g.m

S

= 35.2 g, m

P

=

34.5 g, Mass of 20 spheres = 35.2 34.5 = 0.7 g hence m

= 0.7/20 =

0.035 g. 1

A larger mass measurement, smaller percentage uncertainty in its

value using all 20 spheres gives the average

mass of a single sphere. 1

(c) 12 or more spheres in the groove and d

calculated correctly, e.g. if

12 spheres (

N)

were used and they occupied a total length (

L

) of 36

mm, then; d=L

/

N

= 36/12 = 3.0 mm. 1

(d) Density calculated correctly using density = (6 m

)/(

d

3

) e.g.

Density = (6 x 0.035)/(

0.3

3

) = 2.5 g/cm

3

(2 or 3 s.f.) 2

2(a)

m

W

= 100 cm

3

x 1 g/cm

3

= 100 g. 1

(b) & (c) Accurate interpolation between divisions on thermometer with

correct units. Typical results;

1

= 21.5

C,

2

= 28.8

C 1

(d)

Q

= m

W

c

W

(

2

-

1

) = 0.100 x 4200 x (28.8 21.5) = 3066 J 1

(e) & (f) Typical results; Mass of screw = 6.4 g = 0.0064 kg.

T

= Q

/(

m

S

c

S

) = 3066/(0.0064 x 420) = 1141

Temperature of the Bunsen flame = T

+

2

= 1141 + 29 = 1170

C 1

(g) Sources of error in the experiment are mainly connected with heat

loss e.g. heat conducted through the tongs, heat lost to the air when

transferring the screw to the beaker, heat gained by the beaker as

well as the water. 1

3(a) Light is reflected from the back or silvered surface of the mirror. 1

(b) Normal drawn correctly, perpendicular to the line ABC at the point

B.

Angle of incidence correctly drawn as 35

1

(c) & (d) Initial angle of reflection and position of the line XY correct on thediagram. 1

(e) Position of new reflected ray judged to be correct by eye. 1

(f) Correct value 50

. A value between 47

and 53

is acceptable. 1

8/14/2019 Paper 3 Jun 1999 Physics

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Answer guide for O Level Physics (5054/3) Paper 3 Practical Test June 1999

Page 2 of 2 UCLES 2002

4(a), (b) &

(c)

Check that the metre rule is vertical either by aligning it with a

vertical door or window frame / by using a set square against a

horizontal bench. 1

Candidates should state how parallax is avoided i.e. by keeping the

eye level with the bottom of the length of rubber or by using a setsquare against the vertical rule 1

h

and h

0

recorded to the nearest mm and e

found by subtraction. 1

(d) Results tabulated with quantities and units in the headings of the

table including values ofh,

e

and

W

. All W

values should be in

newtons

e.g. a mass of 50 g (= 0.050 kg) has a weight W

of 0.5 N. 1

This experiment should produce a curve whose gradient is

increasing with increasing force. Six points within 2 mm of curve 1

mark, eight points 2 marks. 1(e) The axes of the graph labelled with the appropriate quantity and

units e.g. extension/mm and force/N. The scale not based on 3, 7, 11

etc.

Data plotted fills more than half the page in either direction. 1

Points plotted carefully with smooth neat curve drawn. 1

(f) The extension when the plasticene is suspended from the paper clip

should be determined. 1

The line on the graph should then be used to determine the

corresponding weight W

P

of plasticene. 1Supervisors provided a mass of 55 g of plasticene. This would have

a weight of 0.54 N. Weight in the range 0.49 N to 0.59 N 1

(g) When the plasticene is fully immersed in water the extension of the

length of rubber should reduce, leading to a weight of approximately

0.25 N. 1

A value in the range 0.20 N to 0.30 N gains a mark for accuracy. 1

(h) Density = kW

P

/(W

P

W

W

) = 1.00 x 0.54 / (0.54 0.25) = 1.86 g/

cm

3 quoted to 2 or 3 s.f. with units g/cm

3

2