# Physics mcq please help

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Thread starter 5 years ago
#1
Four identical rods have a square cross-section. The rods are placed side by side and their total
width is measured with vernier calipers, as shown.
vernier calipers
four square
cross-section rods
1
The measurement is (8.4 ± 0.1)mm and the zero reading on the calipers is (0.0 ± 0.1)mm.
What is the width of one rod?
A (2.10 ± 0.025)mm
B (2.10 ± 0.05)mm
C (2.1 ± 0.1)mm
D (2.1 ± 0.2)mm

Answer is B
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5 years ago
#2
The are two errors that must be added - the zero and measurement.
Divide width and error by four.

Not sure that 3 significant figures should be quoted with confidence.
Need to think about that
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4 years ago
#3
The previous answer is correct ..what is more the zero error should be 0.025.add also error of the measurements 0.1 ÷ 4 = 0.025 ..now the total error will be 0.05 which is found only in answer B.about zero error 0.1÷8.4)×100=1.19....1.19×2.1/100 =0.025
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