UNIT 4 5 6 7 Flashcards
What is energy
amount of work done and measured in joules
how does an object get energy
due to its motion or position
what is the conservation of energy
energy cannot be created or destroyed when work is done, ENERGY IS CHANGED FROM FORM TO ANOTHER
conservation of energy example
some energies are transformed from one form to another sometimes they transform into forms we do not want such as thermal or sound energy
energy type
Kinetic energy, G.P.E
chemical energy, elastic potential energy, nuclear energy, internal energy,
electric energy, light, and sound
kinetic
Due to motion =Car moving
g.p.e
from potential fall= book shelf
chemical
in chemical bonds =bonds in starch
elastic potential energy
compress/stretch = streached elastic band
nuclear
atoms rearrange /split= released in nuclear lant or uranium
electrical
carried by electrons = battery to the bulb
internal
motion of molecules =in a lass of water
light
carried by light waves =from sun or lamp
sound
carried in sound waves =from speaker
calculate ke
1/2 mv<2>
a van mass is 2000kg is travelling at 10 m/s.
calculate its kinetic energy if it increases by 20m/s by how much does it increase
step1: calculates vans ke at 10m/s = 100,000 j / 1000 =100kj step2: calculate vans ke at 20m/s = 400,000j/1000 =400kj step 3 : 400kj-100kj = 300kg
gpe equation
=weight
x-height
Example of conversion of energy
A book on a shelf has
g.p.e, if it falls off the shelf it will have k.e
Efficiency
π¬πππππππππ =
πΌπππππ ππππππ ππππππ/
π¬πππππ πππππ
Γ πππ%
how much useful work is done with energy
supplied
moment
turning effect of a force
M=f*d
weight
mass*gravity /10/
equilibrium
clockwise = anti clockwise
no resultant force and no reslutant moment
Hookeβs law
f=ke
frorce= spring constant * extension
the pressure of a solid
for per area
p=f/a
liquid pressure
densitydepthacerleration due to gravity
manometer
A manometer measures the pressure difference. β’ The height difference shows the excess pressure in addition to the atmospheric pressure.
barometer
Tube with vacuum at the top and mercury filling the rest. β’ Pressure of the air pushes down on reservoir, forcing mercury up the tube. β’ Measure height of mercury β’ ~760 mm of mercury is 1 atm.
