In order to stop a moving object you are supposed to bring down the kinetic energy of that object down to zero.<br /><br />Here, the kinetic energy of the car is 0.5*1500*(72000/3600)^2=300,000J=300kJ. The work required = -K.E=-300kJ
that will turn out to be 15kJ of kinetic energy. So the amount of work required will be -15kJ.
oh, there is a mistake here you have to use 0.5m(v^2). I forgot to use that. The answer should come out to be 300kJ
okk thnkx