UNIT 1 - Energy Concepts Flashcards
Define work and the equation for it
The product of force and distance moved in the direction of the force when the force is constant
Work done = Force x cos(angle) x distance
W=Fcos(angle)X
(Joules)
Equation becomes w=fx if there is no angle or angle is 0
Define energy
Ability to do work (Joules)
Is energy and work scalar or vector
Both scalar
What is the principle of conservation of energy
Energy cannot be created or destroyed, only transferred from one form to another. Energy is a scalar
Equation for kinetic energy
E = 1/2mv²
Kinetic energy(J) = 1/2 x mass(kg) x speed²(ms⁻¹)
What is gravitational potential energy
The energy possessed by an object due to its position or height above the earth
How to derive equation for gravitational
W = fx
F= ma (a = g, gravitational field strength)
W = mgx
Distance = height
gpe = mgh
Gravitational potential energy = mass x gravitational field strength x height
Define kinetic energy
Energy possessed by a moving object
Define elastic potential energy
Potential energy stored as
a result of deformation of an elastic object.
(Such as the stretching of a spring)
Equations for elastic potential energy?
PE = 1/2kx²
or
Pe = 1/2Fx
Equation for spring constant
K = f/x
Explain how KE and GPE changes at points when a ball is thrown into the air
As its thrown into the air KE decreased and GPE increases, KE>GPE
At some point it then stops, KE has decreased to zero and GPE has reached maximum
It then starts to fall back down, as it falls back down KE increases, GPE decreases
KE<GPE
How to work out energy lost due to friction?
KE = GPE + heat + sound
GPE = KE + heat + sound
How to work out force or distance of the energy lost due to friction?
Heat + sound = work done
What is power and units
The rate of doing work
Watts(W) or Js⁻¹
Equation for power (thats not
Given)
P = Fv
Power = force x velocity
Equation for efficiency thats not given
% efficiency = useful power output/total power output x 100%
How can efficiency be represented in diagrams
By a sankey diagram
Which are schematic representations of energy transfers in which the width of the arrows used shows the percentage of the total input energy form
What are the 9 types of energy
Kinetic
Gravitational potential
Elastic potential
Chemical
Electrical
Radiant
Internal
Thermal/heat
Sound
Define chemical energy
Energy stored in mixtures of chemicals or chemical compounds (coil, oil, gas)
Define electrical energy
Energy transferred in electrical circuits by the motion of charge carriers such as electrons
Define radiant energy
The energy carried by all types of electromagnetic waves (xrays, uv, infa-red, etc)
Define internal energy
Energy possessed by a body due to the random distribution of the kinetic and potential energies of the molecules which make it up
Define thermal energy
Energy due to the temperature of an object
Define sound energy
Energy produced by vibrating objects
