Rebecca (m=40kg) is at the bus stop when her friends drive up. She can either sit in the front seat or the back seat. The front seat has a coefficient of static friction u=.5 The back seat has a coefficient of static friction u=.7. If she sits in the front seat she has to hold her friend’s books (m=10kg). If she wants to maximize her total static friction force possible, which seat should she most likely take? a) front seat but not the back seat b) back seat but not the back seat c) either the front seat or the back seat

Define: M = mass of Rebecca = 40 kg m = mass of book = 10 kg g = gravity = 10 m/s^2 u(front) = 0.5 u(back) = 0.7 Maximum force of static friction while sitting in the front seat: F(front) = (M + m) g u(front) = (50 kg) * (10 m/s^2) * 0.5 = 250 Newtons Maximum force of static friction while sitting in the back seat: F(back) = M g u(back) = (40 kg) * (10 m/s^2) * 0.7 = 280 Newtons F(back) > F(front), so choice [b]. I am assuming the simplest possible interpretation of the question, there are a few complexities possible.

Wait, does she plan on kickin it in the back or sittin in the front…??? WHICH SEAT CAN I TAKE!!! sublimity you n3rd

Chuckrox8 Wrote: ------------------------------------------------------- > Wait, does she plan on kickin it in the back or > sittin in the front…??? > > > WHICH SEAT CAN I TAKE!!! > > sublimity you n3rd +1000000000000000 extra bonus for calling sub a nerd +1000000

comp_sci_kid Wrote: ------------------------------------------------------- > Chuckrox8 Wrote: > -------------------------------------------------- > ----- > > Wait, does she plan on kickin it in the back or > > sittin in the front…??? > > > > > > WHICH SEAT CAN I TAKE!!! > > > > sublimity you n3rd > > > +1000000000000000 > > extra bonus for calling sub a nerd +1000000 * 0 = 0

Front seat —> 50*9.8*0.5 = 245N Back seat —> 40*9.8*0.7 = 274.4N Take front.

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Digest what I wrote first and wait until it’s “Friday” before going into what I meant by “there are a few complexities possible.” http://youtu.be/CD2LRROpph0

Duh, Rebecca seats in the front, throws the f books out the window and grabs dude’s schl0ng. Coefficient of static friction goes to the roof. Ahhh, the youth.

Inner Evil Voice Wrote: ------------------------------------------------------- > Duh, Rebecca seats in the front, throws the f > books out the window and grabs dude’s schl0ng. > Coefficient of static friction goes to the roof. > Ahhh, the youth. Wouldn’t the grabbing of the dude’s schl0ng eventually result in a significant decrease in the coefficient of static friction due to the addition of a lubricant?

Since we’re on this topic: http://www.theonion.com/articles/dead-teenager-remembered-for-great-hand-jobs,19356/

higgmond Wrote: ------------------------------------------------------- > Wouldn’t the grabbing of the dude’s schl0ng > eventually result in a significant decrease in the > coefficient of static friction due to the addition > of a lubricant? True dat. Since there is a number of Physics enthusiasts on AF, maybe someone will come up with the friction coefficient curve over time, FC(t) from say t=0 min to t=20 min.

Inner Evil Voice Wrote: ------------------------------------------------------- > higgmond Wrote: > -------------------------------------------------- > ----- > > Wouldn’t the grabbing of the dude’s schl0ng > > eventually result in a significant decrease in > the > > coefficient of static friction due to the > addition > > of a lubricant? > > True dat. Since there is a number of Physics > enthusiasts on AF, maybe someone will come up with > the friction coefficient curve over time, FC(t) > from say t=0 min to t=20 min. Good point about the curve over time, as it will evolve into an adhesive.

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