An uncontrolled zoos kg car strikes squarelya motorway crash cushion in which the car is brought to rest by successively crushing steel barrels. The length of the crash cushion is 15 m, and the magnitude F of the force required to crush the barrels as a function of the distance x the car has moved into the cushion is given by as 1:}: {o s x 5 13111) 135m { 1.35 x 5 4.1m) 150m { 4.15 x 5 15m) 3) Determine an expression for the work done by the force F as a function of x