Kognity IB Physics A.0 Measurements & Uncertainty (id: d206553aa)

[单选题]
The time for two even;foem x mt 9u+la2wi94ts, a and b, are measured to b*qpe5b*q9 /2yona k6; ypxlr be $(5.1 \pm 0.1)s$ and $(4.9 \pm 0.1)s$ respectively. In which of the following quantities is the fractional(percent) uncertainty the smallest?

A. $a+b$
B. $a-b$
C. $a \times b$
D. $a/b$


参考答案:  A


本题详细解析:
C and D will both haw en+q1an5t8 uve identical fractional uncertainties. They cannot both be the smallest, so they must both be incorrect. A and B will have the same absolute uncertainty (0.2 s), but A is a large number (10) comparetua58qe 1+nnw d to B (0.2). Hence fractional uncertainty of A is the smallest.