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

[单选题]
The length of a pencil lt(ljvxmvz4d3i0ajl5,siyt)47 /uk is d (q:-miwb+iv.wfa)c measured using part of a measuring tape as shown belowwim-w f(i+)c.qdabv :.

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 5b u03c( belf sa9lw.rb j4jy.cm scale! The uncertainty in a reading on a scale is usually taken as half the smalwjbl40j5y9 ef(a 3u.s.bc rbllest 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 measurements - one for each end of the pencil. This means that we must also add the uncertainties, giving an uncertainty of 0.5cm.