[填空题]
A train travels $64.7 \pm 0.5$ meters in $8.650 \pm 0.05$ seconds. What is the absolute uncertainty in its speed? (Leave your answer to two significant figures, without units and without the $\pm$ symbol.)
参考答案: 0.101
本题详细解析: Calculating the speed gibz,z:wb 0v*s6 ytsn b7r9q f(cves: $$v=\frac{d}{t}=\frac{64.7 \mathrm{~m}}{8.65 \mathrm{~s}}=7.48 \mathrm{~m} \cdot \mathrm{s}^{-1}$$ The uncertainty on the speed is given by: $$\frac{\Delta v}{v}=\frac{\Delta d}{d}+\frac{\Delta t}{t}$$ so: $$\frac{\Delta v}{7.48}=\frac{0.5}{64.7}+\frac{0.05}{8.65}$$
and: $$\Delta v=0.1 \mathrm{~m} \cdot \mathrm{s}^{-1} .$$ Giving the final value, $$\mathrm{v}=7.5 \pm 0.1 \mathrm{~m} \cdot \mathrm{s}^{-1}$$
