Work and energy

• When a force acts on a moving body, energy is transferred. The energy transferred is known as work done
• work done = force x distance moved in the direction of force
• An object can possess energy of its motion, position and deformation
• When work is done, energy is transferred between types of energy, but the total amount of energy must remain constant. This is known as conversion energy
• Dissipative forces, such as friction acting on the objects may cause some energy to be transferred into thermal energy
• The linear arrangement between force and extension can be written as F=kx

  force = spring constant x extension
• the work done in stretching a spring is equal to the elastic energy stored in the spring
• The work done in stretching a spring can be calculated by finding the area under the force-extension graph, for a linear relationship
• Kinetic energy is the energy an object possesses due to it's motion
• Gravitational potential energy is the energy an object posses due to it's position
• Aerodynamic losses can be reduced by using more streamlined designs; this means the air resistance acting on the vehicle will be less
• rolling losses can be reduced by having correctly inflated tyres
• Idling losses occur when a vehicle is stationary. Start-stop systems automatically stop and restart the engine to reduce this
• Inertial losses are reduced by using lighter materials
• By improving the efficiency of vehicles, they will use less fuel to travel the same distance. This has two main advantages:

  • Using less fuel means that the cost of a journey is reduced
  • Burning less fossil fuel reduces the greenhouse gasses produced which cause global warming
• Crumple zones are areas of a car which change shape or compresses during a collision