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

[单选题]
The length of a pencil is m*xk 13lteheu7s* /,qmhgb*hieasured using dfh+gj :.gai8 px,ev;part of a measuring tape as shown below.ei, a+v: jgpdf ;.hxg8

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 on a scale is22+.6, c pyx+;nvc 5ran: kzen xdyygk usually taken as half the smallest division. Here the smallest division is 0.5 cm so we can read each xkpy +ya 2ne+2r:ky65c c;x. ,zdnnvgpoint 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.