How Do You Calculate the Average Speed for a Round Trip?

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SUMMARY

The average speed for a round trip where a car travels to a destination at 42 km/h and returns at 52 km/h is not simply the arithmetic mean of the two speeds. Instead, the correct calculation involves using the formula for average speed, which is total distance divided by total time. For a round trip of distance x, the average speed is calculated as 2x / (x/42 + x/52), resulting in an average speed of approximately 46.2 km/h.

PREREQUISITES
  • Understanding of basic physics concepts, specifically speed and distance.
  • Familiarity with the formula for average speed.
  • Knowledge of ratios and their application in problem-solving.
  • Basic algebra skills for manipulating equations.
NEXT STEPS
  • Study the formula for average speed in detail.
  • Learn how to apply ratios in physics problems.
  • Practice calculating average speeds for different scenarios.
  • Explore the concept of harmonic mean as it relates to average speeds.
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Students studying physics, educators teaching motion concepts, and anyone interested in solving average speed problems in real-world scenarios.

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A car travels along a certain road at an average speed of 42 km/h, and returns along the same road at an average speed of 52 km/h. Calculate the average speed for the round trip, to within 0.1 km/h.

i have no clue. I'm trying to help a friend with general Physics homework (i've taken physics with calc) but i can't get this very simple question. please help!
 
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This thread should be in the homework sub-forum.

Anyway, how long does it take for the car to travel to a destination a distance x away?
How long does it take to get back?
 
that wasnt given so idk.
 
It doesn't matter what x is, it should come out the same since we are talking about ratios.
 
ok so how do u get it?
 
If its the same distance, then you just need an average of 42 and 52.

42+52=94

94/2= 47km/h
 
it's not it. we've tried that. the question is weird. =/
 
mbayabo said:
A car travels along a certain road at an average speed of 42 km/h, and returns along the same road at an average speed of 52 km/h. Calculate the average speed for the round trip, to within 0.1 km/h.

Hmm, well if that's the EXACT wording of the question, I have no idea. Sorry.
 

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