How Do You Calculate Arc Length and Average Speed with Significant Figures?

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SUMMARY

The discussion focuses on calculating arc length and average speed while applying significant figures. For the first problem, the arc length of a circular arc with a radius of 8.1 cm and an angle of 1.6 radians is calculated using the formula \( L = r \theta \), resulting in an answer of 13 cm when expressed with two significant figures. The second problem involves calculating Mizuki Noguchi's average speed during the 2004 Women's Olympic Marathon, which is determined by converting the total distance of 26 miles and 385 yards into meters and dividing by the total time in seconds, yielding an average speed of 2.92 m/s when expressed with four significant figures.

PREREQUISITES
  • Understanding of circular geometry and the formula for arc length
  • Knowledge of converting units from miles and yards to meters
  • Familiarity with calculating average speed using distance and time
  • Proficiency in applying significant figures in mathematical calculations
NEXT STEPS
  • Study the formula for arc length in circular geometry
  • Learn unit conversion techniques for distance measurements
  • Explore the concept of average speed and its calculation
  • Review the rules for applying significant figures in calculations
USEFUL FOR

Students in mathematics or physics courses, educators teaching geometry and kinematics, and anyone needing to apply significant figures in scientific calculations.

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Homework Statement



1)
How long a piece of wire would you need to form a circular arc subtending an angle of 1.6 rad, if the radius of the arc is 8.1 cm?
Express your answer using two significant figures.

2)
In 2004 Mizuki Noguchi of Japan won the Women's Olympic Marathon, completing the 26 mi, 385 yd course in 2 h, 26 min, 20 s. What was Noguchi's average speed, in meters per second?

Express your answer using four significant figures.
 
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Welcome to PF,

What are your thoughts so far? Can you show us your approach or your attempts? The other two parts of the homework help question template are equally important. What are the relevant relations or concepts that apply here (2), and what steps have you taken (3)?

By the way, neither of these problems is actually about significant figures. The first one tests your knowledge of the radian system of angular measure, and the second one has to do with the definition of average velocity.
 
Is your problem about the number of significant figures? If it is, simply calculate the answer, and round off so that you present an answer with two digits.

86.725235 on your calculator becomes 87,

941.2 becomes 940

7.5912304 becomes 7.6, etc.
 

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