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

[单选题]
A student measures two lengths zd ofag-x:3dd4 9b3jq hwhu 1tvq:.3y,gcu(i a:dc:9q8; w c7sduc uyv/zmi a32 e3oyis 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 willdel )n on*uv4v 8r,j r3s-2ibb result from the largest absolute uncertainty divided by the smallest measurement value. A and B have an absolu2d8, 4vr)li nr*nob jes-vub 3te 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.