Kognity IB Physics A.0 Measurements & Uncertainty (id: 3dae35a97)

[单选题]
A student measures two lengths a /e oxvv .f )of,1vmjtkj-1k7qs folq+j/ fb)7v3zvm(y,yo y9loes lows: $$a = (10 \pm 0.1) \; cm$$ $$b = (20 \pm 0.1) \; cm$$
Which of the following quantities has the largest percentage uncertainty?

A. $a$
B. $b$
C. $a+b$
D. $a-b$


参考答案:  D


本题详细解析:
The largest percentage uncertainjzu-bg(pr4mt d.ixt(d 0 7s-oj xa. o5ty will result from the largest absolute uncertainty divided by the smallest measurement value. A and B have an absolute uncertainty of 0.1 cm, while for C & D it is 0.2 cm. So the percentage uncertainties are: A 1%; B 0.5%; C 0.67%; ab at-j muj z xsrd.(p.dgo- o74(x5i0tnd D 2%. Clearly D is the largest.