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

[单选题]
The length of a pencil ld7dljrxt,l/5 ua5 engtn,/,is measured using part of a measuring tape as shownzs6g6 t4w ktx 94r8rk5n+ihl w belows kt kg46rz xt4w8hn6wi+9l5r.

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 scodu 5(9u7(+d el+kfj wxtr-s xale! The uncertainty 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 each point on the scale to an accuracy of 0.25 cm. To find the length of the pencil we must take twou95 uje+xodk-x7l(rt fw+sd ( measurements - one for each end of the pencil. This means that we must also add the uncertainties, giving an uncertainty of 0.5cm.