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

[单选题]
The length of a pencinr9mfir4)61 )vrc nswl i*ofjgw sa d 2o -:yvj;m2)l4jis measured using part of a measuring tape as shown below.ay*-dm24)o j:oli2j w;v jsgf

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 uncertainty9p5ol5 a83bv k *(vsbz lrfah9 in a reading on a scale is usually taken as half the smallest division. Here the smallest division is 0.bavb3p k 8ls5a9r f* (9zolv5h5 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 we must also add the uncertainties, giving an uncertainty of 0.5cm.