posted by Kevin on .
How much work must be done to stop a 970 kg car traveling at 115 km/h?
Convert that velocity to meters per second. Then calculate (1/2)MV^2, the kinetic energy (KE). V must be in m/s and the mass M in kg, to get the KE in Joules.
The car must perform an equal amount of work if it is to lose that kinetic energy.
If you are stopping the car, the amount of work that must be performed is a negative number equal to the initial kinetic energy.