Anti-lock brakes are designed to keep a car from skidding. on a wet road the coefficient of kinetic and static friction between the road and the tires are 0.15 and 0.40 respectively. what breaking force is required to cause a 1500 kg car to skid on a wet road? a) 225 n b) 600 n c) 2250 n d) 6000 n

D) 6000 N  
Skidding will happen when the applied force exceeds the static friction. So, assuming that the road is level, let's calculate the force needed to overcome the static friction.  
First, you need to know the normal force pulling the vehicle to the ground.
That's simply the mass of the car multiplied by the gravitational acceleration.
So: 
1500 kg * 9.8 m/s^2 = 14700 kg*m/s^2 = 14700 N = 15000 N (after rounding to 2 significant figures). 
 Now multiply by the coefficient of static friction. 
15000 N * 0.40 = 6000 N 
 So the answer is "D) 6000 N"

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