Answer :
Final answer:
The number 0.00091543 has 4 significant figures, the combined weight is 114.22 lbs, the time is less certain by approximately ± 0.20 s, and the bullet train's speed contains an uncertainty of about 1.25%.
Explanation:
Q1. The given measurement is 0.00091543. In this number, zeros leading the non-zero digits are not considered significant. So, this number has 4 significant figures.
Q2. To determine the combined weight, we simply add the three individual weights, 31.2 lbs + 38.02 lbs + 45 lbs. That gives a result of 114.22 lbs.
Q3. The uncertainty in time measurement can be found by multiplying the measurement with the percentage uncertainty. So, we have 11.5 s * 1.7/100 which equals 0.1955 s. So, the time is 11.5 seconds ± 0.1955 seconds, which we can round to 11.5 s ± 0.20 s keeping the same number of digits after the decimal place.
Q4. To calculate the percent uncertainty in the train's speed, we divide the uncertainty (3.9 mph) by the measured speed (312.0 mph) and multiply by 100. That gives us roughly 1.25%, which is the percent uncertainty in the speed of the bullet train.
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