Posted by **engmath** on Monday, February 22, 2010 at 9:52pm.

A car traveling on a flat (unbanked) circular track accelerates uniformly from rest with a tangential acceleration of 1.70 m/s2.The car makes it one quarter of the way around the circle before it skids off the track. Determine the coefficient of static friction between the car and track from these data.

I thought the answer was 0.5449 but its wrong. no matter what I do i keep getting the same answer!

- Physics -
**bobpursley**, Monday, February 22, 2010 at 11:24pm
Why would you think the answer is .5446? I will be happy to critique your work

- Physics -
**bobpursley**, Monday, February 22, 2010 at 11:27pm
you need to round off to three sig digits

- Physics -
**engmath**, Tuesday, February 23, 2010 at 12:15am
α=a/r

the time it takes to travel π/2 radians is

related by

π/2=.5*a*t^2/r

solve for t

t=sqrt(π*r/a)

ω=α*t

Plug in t and a/r

ω=sqrt(a*π/r)

The force is m*ω^2*r

F=m*a*π

friction is

m*g*µs

then

m*g*µs=m*a*π

so basically....

µs=a*π/g

=1.70pi/9.8= 0.54497 ====> sig figs 0.545

- Physics -
**engmath**, Tuesday, February 23, 2010 at 12:16am
and that answer comes up as incorrect...

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