Topic 3 - Work and Energy

• State the law of conservation of energy.

  Energy in = energy out (usually it means kinetic=potential).
• What are aerodynamic losses and how can they be reduced?

  Energy lost by air resistance - streamline the car
• What are rolling losses and how can they be reduced?

  Friction - pump up the tires
• What are idling losses and how can they be reduced?

  At traffic lights not moving bu the engine is running - stop/start the engine
• What are inertial losses and how can they be reduced?

  Heavier cars use more energy - use carbon fibre
• Explain how airbags, crumple zones and seatbelts can reduce injury during a crash.

  All of them reduce the energy and the force of impact by increasing the time it takes to stop.
• What do headrests protect against?

  Whiplash
• What is a roll cage used for?

  Stops the roof from collapsing if the car is upside down
• Explain how you would find the spring constant of a spring.

  Measure the length of a spring, hang a weight on it and measure the extension

  Force = spring constant × extension

  (if we plot force on the y axis and extension on the x axis then spring constant = gradient)
• What does spring constant mean?

  The stiffness of the spring