Conservation Of Energy Flashcards
What is energy?
The capacity of an object doing work
What is the principle of the conservation of energy?
Energy cannot be created or destroyed it can only be transferred from one form to another
Kirchhoff’s second law
The sum of the e.m.f’s in a closed circuit equals the sum of the potential differences
- Conservation of energy
Kirchhoff’s first law
The sum of the currents entering a junction always equal the sum of the currents out of the junction
- Conservation of charge
Define work
The amount of energy transferred when an external force causes an object to move over a certain distance
What is an energy store?
When energy is stored in an object
Types of energy stores
- Elastic potential energy
- Gravitational potential energy
- Chemical energy
- Nuclear energy
- Internal energy
What is energy transfer?
When energy is moved or causes movement
Types of energy transfers
- Kinetic energy
- Sound energy
- Light energy
- Electrical energy
What does work done mean?
When energy transfers from one store in a system to another store in a system, work is done
Factors that affect the work done when moving an object
- Size of the force - the bigger the force the greater amount of work done
- The distance - the further you push the object the greater amount of work done
Equation for work done
Work done = F x V
Units for the joule
1 J =1 N⋅m
Define 1 joule
The work done on an object when a force of 1N acts on an object parallel to its motion through a distance of 1m
SI Base unit for 1 Joule
kg m² s⁻²
What is the area under a force against distance graph?
Work done of an object
What happens when work is done against friction?
It will cause heat energy to be transferred to internal energy of the surroundings
How to calculate the work done by a force in a direction
W = F x cos0
How can you calculate work done?
Work done = Force x displacement
W = F x d
At an angle —>
W = F x d x cos0
How do you calculate gravitational potential energy?
GPE = mgh
How do you calculate kinetic energy?
1/2mv²
Definition and equation for power
Rate of work done
P = W/t
SI base units for power
Kg m² s⁻³
Define efficiency
A measure of how much energy is conserved as useful energy
Useful energy/ Total energy x 100
