High School

A marathon runner completes a 42.884 km course in 2 hours, 11 minutes, and 52 seconds. What is the uncertainty in the distance run and the elapsed time?

Answer :

Final answer:

The percent uncertainty in the distance is 0.0592%, the uncertainty in elapsed time is 1 s, the average speed is 4.68 m/s, and the uncertainty in average speed is 0.0031 m/s.

Explanation:

(a) To calculate the percent uncertainty in distance, we can use the formula: percent uncertainty = (uncertainty / measured value) * 100%. In this case, the uncertainty in distance is 25 m and the measured value is 42.188 km (which is equivalent to 42,188 m), so the percent uncertainty in distance is: (25 m / 42,188 m) * 100% = 0.0592%.

(b) To calculate the uncertainty in elapsed time, we simply need to use the given value of 1 s.

(c) Average speed is calculated by dividing distance by time. In this case, the distance is 42.188 km (or 42,188 m) and the time is 2 hours, 30 minutes, and 12 seconds (which is equivalent to 2*3600 + 30*60 + 12 = 9012 seconds). So the average speed is: 42188 m / 9012 s = 4.68 m/s.

(d) To calculate the uncertainty in average speed, we can use the formula: uncertainty in average speed = average speed * (percent uncertainty in distance + percent uncertainty in time). In this case, the average speed is 4.68 m/s, the percent uncertainty in distance is 0.0592%, and the percent uncertainty in time is (1 s / 9012 s) * 100% = 0.0111%. So the uncertainty in average speed is: 4.68 m/s * (0.0592% + 0.0111%) = 0.0031 m/s.

Final answer:

  • The percent uncertainty in the distance is 0.05922%
  • The uncertainty in elapsed time is 1 s
  • The average speed is 5.355 m/s
  • The uncertainty in average speed is 0.0312 m/s.

Explanation:

(a) To calculate the percent uncertainty in the distance, we divide the uncertainty by the measured distance and multiply by 100.

Percent uncertainty in distance = (uncertainty in distance / distance) x 100

Percent uncertainty in distance = (25 m / 42188 m) x 100 = 0.05922%

(b) To calculate the uncertainty in the elapsed time, we simply take the given uncertainty.

Uncertainty in elapsed time = 1 s

(c) Average speed is calculated by dividing the distance traveled by the elapsed time. We convert the time to seconds and the distance to meters for consistency.

Average speed = distance / time

Average speed = 42188 m / 7872 s = 5.355 m/s

(d) To calculate the uncertainty in the average speed, we use the formula:

Uncertainty in average speed = (uncertainty in distance / distance) x average speed

Uncertainty in average speed = (25 m / 42188 m) x 5.355 m/s = 0.0312 m/s

Your question is incomplete, but most probably the full question was:

A marathon runner completes a 42.884 km course in 2 h, 11 min, and 52 s. What is the percent uncertainty in the distance, the uncertainty in elapsed time, the average speed, and the uncertainty in average speed?