Chapter 7 energy Flashcards
What kind of quantity is energy
Scalar quantity because it only has magnitude and no direction
What is energy
Energy is required for things to work. Energy is the ability or capacity to do work.
What is the SI unit of energy
joules ( J )
What are the different energy stores
Elastic potential store
Kinetic store
Internal store
Nuclear store
Gravitational potential store
Chemical potential store
What are the four different pathways energy can be transferred from one store to another
Energy transferred mechanically by a force acting over a distance
Energy transferred by heating due to temperature difference
Energy transferred by propagation of waves (electromagnetic waves OR mechanical sound waves)
Energy transferred electrically by an electric current
What is kinetic energy
It is the energy possessed by a body due to motion
What is the formula of energy in kinetic store
E k = 1/2 mv^2
What is potential energy
It is the energy possessed by a body due to postion
What is the formula of energy in potential store
E p = mgh
What is the principle of conservation of energy
The principle of conversion of energy states that energy cannot be created or destroyed. Energy can be transferred from one store to another. The total energy of an isolated system is constant.
What can you conclude from the principle of conservation of energy
No new energy is formed
Total existing energy cannot be destroyed
Energy can only be transferred from one store to another.
What is work done
Work dome by a constant force on an object is the product of the force and the distance moved by the object in the direction of the force.
What is the formula for work done
W= Fs
What is power
Power is defined as the work done or energy transferred per unit time
What is the formula for power
P= W/t = E/t = F x V
