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

[单选题]
The length of a penci5y0m8 :pehma lpc2,ha l is measured usin 9fzo hbuv)f+5n:7z gng part of a measuring tape as shown below 7nz nu)ghob59f:v+z f.

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 uncertai7qf:ylut0qgkp nzk, wt*7gck q0 nd3-008xfi nty 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 two measurements - one for each end of the pencil. This met-u iqkk0fnqq gzfn 87w3p7l:c dt00gxy0k* ,ans that we must also add the uncertainties, giving an uncertainty of 0.5cm.