4. A 1200.0-kg car is traveling at 19 m/s . The driver suddenly slams on the brakes and skids to a stop. The coefficient of kinetic friction between the tires and the road is 0.80. For what length of time is the car skidding?

5. An object attached to a spring is being pulled across a flat frictionless surface. The spring constant is 48 N/M, the object is accelerating at 1.1 m/s², and the mass of the object is 38 kg. What distance is the spring stretched?

energy equation which is broken down to (change in PE+KE)=nonconservative forces*distance(which is also energy)=>1/2mv^2=Fd where F is a force and d is the distance F would be friction force which is normal force (force of gravity in this case) * coefficient of friction(mu).... simplified (1/2v^2)/(mu*g)=d=23.023meters

Same idea as before

F=ma; Fd=1/2kx^2 where d is the distance the force is acting over and x is the distance stretched (which in this case x=d) ... simplified 2ma/k=x=.871meters