P1 conservation and dissipation of energy Flashcards
What is the conservation of energy?
Energy cannot be created or destroyed, only transferred between different stores
What energy transfers happen to a bungee jumper?
Gravitational potential to kinetic of human to elastic potential of rope to kinetic as it goes back up to gravitational potential and so on
Why does a bungee jumper not return to their original height?
Some energy is lost through thermal energy store of the surroundings
Relationship between work done and energy transferred
Work done = energy transferred
Work done equation
Work done = force x distance (W=Fs)
Units in work done equation
Work done = Joules (J)
Force = Newtons (N)
Distance = Metres (M)
When does an objects gravitational potential energy change
When an object is raised, it increases and when it is lowered, it decreases
Gravitational Potential Energy equation
Energy = mass x gravitational field strength x height (E = mgh)
Units in gravitational potential energy equation
Energy = Joules (J)
Mass = Kilograms (kg)
Gravitational field strength = Newtons per kilogram (N/kg)
Height = metres (m)
Kinetic Energy equation
Energy = 1/2 x mass x velocity^2 (E=1/2mv^2)
Units of kinetic energy equation
Energy = Joules (J)
Mass = Kilograms (kg)
Velocity = metres per second (m/s)
Hooke’s law
F = ke
Force = spring constant x extension
Elastic potential energy equation
Energy = 1/2 x spring constant x extension^2
(E = 1/2ke^2)
Units of elastic potential energy equation
Energy = Joules (J)
Spring constant = Newtons per metre (N/m)
Extension = Metres (m)
What is wasted energy
Energy not usefully transferred
