Posted by **Elizabeth** on Sunday, October 3, 2010 at 10:11pm.

A car is traveling at 54.2 km/h on a flat highway. The acceleration of gravity is 9.81 m/s^2.

PART 1: If the coefficient of kinetic friction between the road and the tires on a rainy day is 0.131, what is the minimum distance needed for the car to stop? Answer in unitsof m.

PART 2: What is the stopping distance when the surface is dry and the coefficient of kinetic friction is 0.603? Answer in units of m.

- Physics -
**MathMate**, Sunday, October 3, 2010 at 10:55pm
Frictional resistance, F

= -μ mg

acceleration, a

= F/m

= -μg

For distance S, use

v²-u²=2aS

where v=final velocity =0

u=initial velocity = 54.2 km/h = 15.06 m/s

Solve for S.

1. μ=0.131

u=54.2

a=-0.131*9.8=-1.284 m/s²

S=15.06²/(-2*1.284)

=88.3m

The same approach can be used for both cases.

Post your answers for a check if you wish.

- Physics -
**Elizabeth**, Sunday, October 3, 2010 at 11:06pm
omg thx so much!!!!

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