Here's the equation; remember you need to learn this. Kinetic energy is 0.5, multiplied by the mass, multiplied by the speed squared. The mass is 100 kilograms, and the speed is 15 metres per second. Putting these numbers into the equation gives us a kinetic energy of 11,250 joules. Dividing this by 1,000 gives us 11.25 kilojoules.