Calculate the acceleration of the cyclist

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The discussion revolves around calculating the acceleration of a cyclist who comes to a stop from a speed of 21 km/h over a distance of 15 meters. The student initially attempts to use the formula v1^2 - v2^2 = 2 * d * a but struggles to find the correct answer. After converting the speed to meters per second, the calculated acceleration is approximately -0.00649 m/s². The student also explores the coefficient of friction, concluding that mass does not affect the calculations. The conversation highlights the importance of understanding the physics principles involved in motion and friction.
bonfire89
Question...
Hi, I'm a Grade 11 physics student who is having a difficult time on this one question.. Any help would be greatly apretiated.


A cyclist is traveling at 21km/h when she sees a stop sign ahead. She applies the brakes and comes to a stop in 15m. The mass of the cyclist and the bike is 73kg.

a)Calculate the acceleration of the cyclist.
b) Determine the coeficient of friction between the road and the bike.


currently for question a I am atempting to use
v1^2 - v2^2 = 2 * d * a
but I am not getting the right answer


Thanks!
 
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21 km/h =~ 5.838 m/s

a = (0 - 5.838)/900 = -0.0064866666666666666666666666666667m/s^2

ΣF = -μkFN = ma

-μkmg = ma

-μkg = a

μk = -(a/g) = 6.6190476190476190476190476183673e-4


as you can see, mass don't matter.
 
awsome! thank you. I am currently doing other porblems, but I shall come back to then, and learn what you did..

THank you!
 
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