Average Speed = distance/time question.

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SUMMARY

The discussion centers on calculating the average speed of a race car on a circular racetrack with a radius of 400 meters. The average speed formula, defined as Total Distance divided by Travel Time, is applied to determine that the car completes a lap in 40 seconds. The correct calculation for the circumference of the track is 2πr, leading to a total distance of approximately 1256 meters. Thus, the average speed is confirmed to be 63 m/s, calculated as 1256 meters divided by 40 seconds.

PREREQUISITES
  • Understanding of the formula for circumference: C = 2πr
  • Basic knowledge of average speed calculation
  • Familiarity with units of measurement (meters, seconds)
  • Ability to perform basic arithmetic operations
NEXT STEPS
  • Study the derivation and applications of the circumference formula C = 2πr
  • Explore the concept of average speed in different contexts, such as linear motion
  • Learn about the relationship between distance, speed, and time in physics
  • Practice solving problems involving circular motion and average speed calculations
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Students studying physics, particularly those focusing on motion and speed calculations, as well as educators looking for examples of average speed in circular motion scenarios.

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Homework Statement


A race car races on a circular racetrack of radius (r).
(a) Write an equation for the car’s average speed when it travels a complete lap in time (t).
(b) The radius of the track is 400m and the time to make a lap is 40s. Show that the average speed around the track is 63m/s.

Homework Equations


Average Speed = Total Distance/ Travel Time

The Attempt at a Solution


(a) speed = distance/time ?

(b) 400m x 3.14 = 1256m.
63m/s = 1256m/40s.. this is where I get lost. This obviously isn't right. I'm getting an average speed of 31.4m/s.
 
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400m x 3.14 = 1256m is not quite right. What's the formula for circumference again?
 
3. The Attempt at a Solution
(a) speed = distance/time ?

(b) 400m x 2 = 800m = diameter
800m x 3.14 = 2512 = distance
63m/s = 2512m/40s = 62.8m/s
 
Last edited:
negitron said:
400m x 3.14 = 1256m is not quite right. What's the formula for circumference again?

Ty again!

It's been awhile ;(
 
Yes, you have it now.
 

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