Kognity IB Physics A.0 Measurements & Uncertainty (id: 294aaa607)

[单选题]
The length of a pencil is measured using part ofb. (4 5r nekmxq 74imj c;x7tfa*fmgd9 a measuring tape as shown bzjxm)+/ *umd93gel y ielow3 9)+jm*lyxme/igzud .

What is the length of the pencil?

A. $4.5 \pm 0.1 \; cm$
B. $11.5 \pm 0.2 \; cm$
C. $11.5 \pm 0.3 \; cm$
D. $11.5 \pm 0.5 \; cm$


参考答案:  D


本题详细解析:
We should be looking at the cm scale! The uncertainty in a reading o5o 01uenxx7l qn a scale is usually taken as half the smallest division. Here the smallest division is 0.5 cm so we can read each point on the scale to an accuracy of 0.25 cm. To find the length of the pencil we must take two measurements - one for each end of the pencil. This means that we57quxn1 o0x le must also add the uncertainties, giving an uncertainty of 0.5cm.