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

[单选题]
The length of a pencob5q3 z0 g*-; 9oxf +ur/zlup.oanuy jil f ojz2 to4v yj)xo-k88is measured using part of a measuring tape as shown below.oj8yvjotofk 4 -8z)2 x

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 readkkcq4 qh92a(x+ai0+ (p more y-hq m)ting on 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 sca (p4oct9 im axqr)q mk2q+-yehah0k(+le 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.