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

[单选题]
The length of a pencil is meo 5l1wxb8 -imbmcdglpw:)fwm 367mu 8n(pwe*ks;b8 n e heq2c2aj5+hasured using part of a measuring tape as shown beloww che5; bqj(*n2+ hs8e2 nekpa.

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 )cfc+ndd 7dm+hyy06gw: boi p)a64w escale! 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 a+6i bwhdc wp4cydo yaegm)0)7+ 6f :dnn 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.