Page 19 - Q & A STPM 2022 Physics

Physics Semester 1 STPM Chapter 1 Physical Quantities and Units
1.4 Uncertainties in Measurements

Section A Multiple-choice Questions
Question 1
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The diagram shows a metre rule. x and x are two scale readings as shown.
1 2

25 26

Semester
1
x 1 x 2

Which of the following shows the correct reading of x and x ?
1
2
x x
1 2
A 25.40 ± 0.05 cm 26.00 ± 0.05 cm
B 25.45 ± 0.05 cm 25.95 ± 0.05 cm
C 25.45 ± 0.05 cm 26.00 ± 0.05 cm
D 25.40 ± 0.05 cm 25.95 ± 0.05 cm

Answer: A
When the reading is not at the middle, always take the reading which is nearer.

Question 2
The length and the width of a rectangle is 12.80 ± 0.05 cm and 23.7 ± 0.05 cm
respectively. Find the area of the rectangle.
A 304.5 ± 0.1 cm 2
B 305.8 ± 0.1 cm
2
C 304 ± 2 cm 2
D 305 ± 2 cm 2

Answer : C
A = L × W
A = (12.80 × 23.75) ± ∆A
= 304 ± ∆A

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01 STPM Q&A PHY T1.indd 10 17/02/2022 10:03 AM