Fatal impact – the physics of speeding cars
Glossary
frictional resistance. Friction is a force that impedes the slipping or sliding of two surfaces in contact. The frictional resistance depends on the roughness of the surfaces involved. When a car is skidding, the surface of the tyres and the surface of the road both affect the resistance provided by friction.
kinetic energy. Kinetic energy is the energy associated with a moving object (energy of motion). For more information see Energy basics (Box 3 of Nova: Science in the news topic, Wind power gathers speed).
newton. The SI unit of force. One newton gives an acceleration of 1 metre per second per second to a mass of 1 kilogram. The weight you feel when you hold an average size apple in your hand is about one newton (mass is about 0.1 kilogram and gravitational acceleration of about 10 metres per second per second). It is named after Sir Isaac Newton.
Page updated August 2006.