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

[单选题]
The length of a pencil is meaphfhus 8h sq/d 4-yd5-o8 o8q4xfvkd ;sured using part of a measuring tape as sho)hkxfl74 z to vpk 1l7m9 su,g0jvf:7qwn below.l1o 97txh: pzfqml4v)g70kuvs k 7,fj

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 rexr/2p u7rzh , tcqa-m(ading 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 scale to an accuracy of 0.25 cm. To find the length of the pencil we must take two mq t7(azurcrhx-m/2, peasurements - one for each end of the pencil. This means that we must also add the uncertainties, giving an uncertainty of 0.5cm.