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

[单选题]
The length of a pencil is measured using part of a meeq8 t oot.8 z-; (arg d*bsvb3 t6mto3rpn4.foasuring tape as shown belou3.+8pw ice suw.8cp i seuu+.w3

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! n:i 6f ;1go op+iy*pbcThe uncertainty in a reading on a scale is usually taken as half the smallest division. Here the smallest divisf *6+:cn g;y b1oioippion 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.