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

[单选题]
A student measures tdmk +* i(b7soy //,4dfybp wd9n.e ii7(bza3pnj dsgll77b-lwo lengths as follows: $$a = (10 \pm 0.1) \; cm$$ $$b = (20 \pm 0.1) \; cm$$
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 uncertainty will result from the largei:ylbj d 7gea3 (cyo-c.d9fu9st 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 pefega9bd7ycou:-y(d i .jl 93crcentage uncertainties are: A 1%; B 0.5%; C 0.67%; and D 2%. Clearly D is the largest.