A 1500 kg car going 40 9 m/s on a horizontal surface needs to stop in 100m. What minimum force of friction and coefficient of static friction must exist between the tires and the road for this to be able to happen ?
work to stop=1/2 m v^2= 750*40.9^2 joules (you multiply it )
work to stop=force*distance=force*100
set those two equal, and solve for force.
coefficent static friction....
work to stop=1500*9.8*coeffcent
set that term to equal work to stop,solve for coefficent.