20 June 2009

Today's Lesson: Mechanical Advantage

Word Problem: You are on a bicycle, traveling at 25 mph for 27 minutes, into a 5 mph head wind. At 8:17 PM you reduce speed to 15 mph to avoid an oncoming traveler. At exactly 8:18 PM, you ride over a twig, which gets caught in your wheel and disables your bicycle.
From 2009-06 Bike

You realize that the "bike malfunction" is a broken derailleur, which retails for $43.94 + tax.

Question 1: What distance would you have traveled by 9:30 PM assuming constant speed and no breakage?

Question 2: How many nice things can you no longer buy in your new house due to the cost of replacing the derailleur? Can you negotiate a lower price?

Question 3: Calculate the applied force of a twig on the derailluer. The bike wheel is 26" in diameter, the twig is .25" in diamater, and is caught in the spokes 5" in from the rim of the wheel. Forward speed is 15 mph. Show your work.

Question 4: What is the total energy of of the system of 1) the bicyclist, 2) the rescue vehicle & driver and 3) the babysitters who watched the kids while Liesel drove to Huber Heights.

Extra Credit: Explain what the bicyclist could have done to avoid having a mechanical malfunction. Do not use passive voice. Do not use Wikipedia.

5 comments:

Liesel said...

question 5:
What is the probability that just after purchasing a house and thinking that's all you have to worry about, your husband has a bike accident which needs a pricey fix?

Katie said...

I'm just going to answer the Extra Credit question:

Bicyclist should have driven his car.

Anonymous said...

i thought bikes were for kids,,drive two big nails in the new garage wall and say your new home bike,,other than that had a nice fathers day,,give my two gg kids my love great gramp

Rick said...

can this bike really be reliable to trave 320 miles across Ohio now?

Nana said...

Say a prayer of thanksgiving that you did not go head over heels over the handlebar.
Hope you were not hurt. A $50.00 derailleur is a heck of a lot better than a trip to the ER.