Posted by **grace** on Saturday, April 2, 2011 at 10:54pm.

A car is travelling at 42.4 km/h on a flat highway. The acceleration of gravity is 9.81 m/s^2. If the coefficient of friction between the road and the tires on a rainy day is 0.125 what is the minimum distance for the car to stop? Answer is metres

- physics -
**drwls**, Saturday, April 2, 2011 at 11:40pm
First, convert speed (V) to units of m/s.

42.4 km/h = 11.78 m/s

Initial kinetic energy = Work done against friction

(1/2)MV^2 = M*g*Uk*X

M cancels out.

X = V^2/(2*g*Uk) is the stopping distance, if the car is skidding.

If the brakes manage to apply the maximum force that prevents a skid as an automatc braking system (ABS) is supposed to do, the static friction coefficient Us can be used instead of Uk, the kinetic friction coefficient. In that case you get a minimum stopping distance.

They don't say which friction coefficient they are providing.

## Answer this Question

## Related Questions

Physics - A car travleing at 30.6 mi/h on a horizontal highway. The acceleration...

Physics - A car is traveling at 66.9 mi/h on a horizontal highway. The ...

physics - A car is traveling at 60.6 mph on a horizontal highway. The ...

Physics - A car is traveling at 54.2 km/h on a flat highway. The acceleration of...

Physics - A car is traveling at 44.4 km/hr on flat highway. If the coefficient ...

Physics - A car is traveling at 42.0 km/h on a flat highway. (a) If the ...

physics - A car is traveling at 58.2 km/h on a ﬂat highway. The ...

physics - A car is traveling at 51.0 mi/h on a horizontal highway If the ...

physics - A car is traveling at 45.0 mi/h on a horizontal highway. (a) If the ...

Physics - a car enters a 300m radius flat curve on a rainy day when the ...