Math problem

[kibble]

In my math class, we came across a problem in the book that seems very ambiguous and difficult to understand. Even our teacher was kind of confused by it, but she gave it to us to figure out. I'm wondering if any of you think so too. Here's the problem:


"Bicycle Low Gear:

If a bicycle has 26 inch diameter wheels, the front chain drive has a radius of 2.2 inches, and the back drive has a radius of 3 inches, how far does the bicycle travel every one rotation of the cranks (pedals)?"


It even though it says "front" and "back", it doesn't clearly state whether the 2.2" is the crank or the 3" is the cranks, and the answer in the book is different from what we got as an answer, assuming the 2.2" was the crank.

 

[newrider3]

What answer did you get? What steps did you go through to solve it? With my sophistimicated algebraic techniques (read:making **** up as I go along), I got 18.98. For every 1 turn of the cranks, the rear cassette will turn .73 turns. Multiplied by the rear wheel diameter = 18.98.

Keep in mind math is my worst subject, feel free to call me a complete moron.

 

[ed1380]

close. the calculator on the front page does most of it. except it does RPM instead of the needed R.
you do circumfrence times revolutions for distance traveled
26(3.14)*(2.2/3)
59.5972

i dam bette rknow how to do this, seeing as i wanted to go for mechanical engineering

 

[kibble]

close. the calculator on the front page does most of it. except it does RPM instead of the needed R.
you do circumfrence times revolutions for distance traveled
26(3.14)*(2.2/3)
59.5972

i dam bette rknow how to do this, seeing as i wanted to go for mechanical engineering

The answer says: 60" (5ft) so I think you nailed it, Ed!

Congrats, you may go on to mechanical engineering! Now we just gotta work on your spelling. :arf:

I think I tried to make it more complicated than it was supposed to be. Somehow I had like 17".

So it was supposed to be: (2(pi)radius)*(ratio of sprockets).

Newrider, you almost had it, except you forgot to throw in the pi.

 

[ed1380]

english is my second language

i got a problem for you

the sprocket on a clone is 2.2" and the sprocket on your axle is 3". you have 10" diameter wheels on your gokart. how far will you go for every revolution of the engine?

 

[bigfootrules31]

ive got an even more tricky question. what happens when your driving at the speed of light and turn your headlights on??

 

[kibble]

If you were traveling at the speed of light, you wouldn't see anything anyways.

 

[BradenM]

Anybody up for a wee chat about relativity? Lol.