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

[单选题]
The time for two events,eda;q(/nou;7 2df8a e-x sszj a and b, are meyk 63hatngu1 4asured to 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 have identical fractional uncertrtdp(zutu* z/od,mk9 gl9.x .p v5w z;ainties. 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) lkg 5dz(zu.trz9vt9;* d x/pp.,wom ucompared to B (0.2). Hence fractional uncertainty of A is the smallest.