A car moving with a velocity of 20 meters/second has

1.8 * 105 joules of kinetic energy. What is the mass of the car?

Kinetic energy is the product of mass and the square of the velocity of the moving object. In this case, we substitute the given data, that is 1.8 x10^5 joules = m * (20 m/s2) ^2. Extracting the mass, the mass of the car therefore is equal to 450 kg