Energy and Power Flashcards
What is Power?
Power is the rate of transfer of energy (energy transferred per second)
How do you calculate the power of an appliance?
Power = Energy / Time
or
P = E / t
How do you calculate the efficiency of an appliance?
Efficiency = Useful Power / Total Power In (100%)
How do you calculate the Power wasted by an appliance?
Power Wasted = Total Power Input - Useful Power Output
What is Kinetic Energy?
Kinetic Energy is the energy an object has due to it moving
What does the amount of Kinetic energy an object has depend on?
- Mass
2. Velocity (Speed)
How do you calculate Kinetic Energy?
Kinetic Energy = 1/2 x mass x velocity²
or
E(k) = 1/2 x m x v²
What is the equation for Elastic Potential Energy?
Elastic Potential Energy = 1/2 x Spring Constant x extention
or
E(e) = 1/2 x k x e²
What is the Spring Constant?
The amount of energy stored in the spring
Is a bigger or smaller spring constant stiffer?
A bigger spring constant means it is harder for the spring to be compressed and stretched
So
A smaller spring constant means it is easier for the spring to be compressed and stretched
How do you calculate the Spring Constant?
Spring Constant = Force x Extension of the Spring
or
k = F x (Extension of Spring)
What is Gravitational Potential Energy?
The gravitational potential energy (GPE) of an object due to gravity
What does Gravitational Potential Energy depend on?
- Mass
- Gravitational field strength
- Height
How do you calculate Gravitational Potential Energy?
GPE = mass x gravitational field strength x height
What is the relationship between GPE and Kinetic Energy?
The law of Conservation of Energy means that as an object falls the GPE lost must be turned into a different form. This different form is Kinetic Energy.
GPE lost = Kinetic Energy gained
This is only true if air resistance and friction are ignored
