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

[单选题]
A student measures two lengths as fofylv;w- 8wa- 5kjy.pox1 g lr.llows: ix;.cr d)7j4 ukn x.pilbp5 c60xwk9y $$a = (10 \pm 0.1) \; cm$$ $$b = (20 \pm 0.1) \; cm$$
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 unc+/ke2x9/9j nbsk n7bi6 gskhgertainty will result from the largest absolute uncertainty divided by the smallest measurement value. A and6 g /s+gbkknjh i99sk bn7x/e2 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%; and D 2%. Clearly D is the largest.