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

[单选题]
The length of a pencil is mb61 n+f h-gexteasured using part o,6f).idcsq/j o.h;g 5 z znlkrf a measuring tape as shown below.n6,qcg.izsf)./ k jor 5; lzdh

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 uncertaild hh (;7p)urp.q0jvhf 4)s benty in a reading on a scale is usually taken as half the smallest division. Here the smallest division is 0.5 cm so we can read h7s;euh0 .fld ppq )jvh)4(rbeach 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.