P1.7 Energy and efficiency Flashcards
What is weight measured in?
Newtons
What is energy measured in?
Joules
What is the definition of 1 joule?
Amount of energy required to life a weight of 1 newton by a height of 1 metre is equal to 1 joule
What is the input energy?
The energy supplied to the device is called the input energy
What does input energy equal to?
Useful output energy + energy wasted
What is the equation for efficiency?
Useful output energy transferred by the device/ total input energy supplied to the device
Why can no device be more than 100% efficient?
Because you never can get more energy from a machine than you put in
How can you reduce the wasted energy caused by friction between the moving parts?
Lubricate the moving parts to reduce friction and reducing the amount of heat produced
How can you reduce the wire getting hot when a current passes through it?
Use wires with as little electrical resistance as possible
How can you reduce the thermal energy produced by air resistance causing an object to slow down?
Streamline the shapes of moving objects to reduce air resistance
How can you reduce sound created by machinery?
Cut out noise by tighten loose parts
