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

[单选题]
The length of a pencil is measured using pari-p;mjb9a pwa (pn :f5t of a measuring tape as showdof*c*oztz -*z*gu,an below.d o** fgz*otuza-c *,z

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 rea( ahq qdt u5ng7p)380ynau.smding on a scale is usually taken as half the smallest division. Here the smallest division is 0.5 cm so we can read eachd 7npa u yt8agh 3.uq5qsmn)0( 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.