Answer
given,
cooling fan revolution = 850 rev/min
fan turns before revolution = 1500 revolutions
θ = 1500 revolution
θ = 1500 x 2 x π
θ = 9424.78 rad
a) using equation of rotation
ω² = ω₀² + 2 α θ
ω = 0 because body comes to rest
0 = 89² + 2 x α x 9424.78
α = -0.42 rad/s²
b) time take for the fan to stop
ω = ω₀ + α t
0 = 89 - 0.42 t
t = 211.9 s
The answer for sub question A) calculate the percent uncertainty in the distance is 0.059%.
The answer for sub question B) calculate the uncertainty in the elapsed time is 9,012 s
The answer for sub question C) what is the average speed in meters per second is 4.681 m/s
The answer for sub question D) what is the uncertainty in the average speed is 0.0032 m/s
<h3>How are the answers calculated?</h3>To calculate the percentage of uncertainty of distance we have uncertainty = 25 m and distance = 42.188 km which is 42188 m.
Now x 100% = 0.059%
To calculate time elapsed, we have the following data:
2hr which is 7200 s, 30 min which is 1800 s and 12 s
Adding these all up, we get 9012 s.
The average speed in m/s is calculated by 42188 m/ 9012 s = 4.681 m/s
The uncertainty in average speed is calculated by 4.681 m/s x
= 0.0032 m/s
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The complete question is A marathon runner completes a 42.188 km course in 2 h , 30 min, and 12 s . There is an uncertainty of 25 m in the distance traveled and an uncertainty of 1 s in the elapsed time. (a) Calculate the percent uncertainty in the distance. (b) Calculate the uncertainty in the elapsed time. (c) What is the average speed in meters per second? (d) What is the uncertainty in the average speed?
Answer:
Explanation:One method of calculating average speed is to divide the total distance by the total time spent
d1=d2= 12 miles
d1=d2= 19312.1 m
There is slight difference between the average speeds due to the reason that average speed is not just the midpoint of the speed but is the total distance traveled by total time.