Physics Important Notes

  

Prefix	Meaning
giga	109
mega	106
kilo	103
deci	10-1
centi	10-2
milli	10-3
micro	10-6
nano	10-9

 

Non-renewable source:

Fossil fuels: They formed from the remains of plants and tiny sea creatures that lived for millions of years.

Problems: Their waste gases pollute the atmosphere. This adds to global warming.

Nuclear fuels: In a nuclear power station, nuclear fission takes place.

Problems: Waste is dangerous and radioactive. Power stations are expensive to build and dismantle.

Renewable source:

Hydroelectric energy: The river fills the lake behind the dam. Water flows down from the lake and turns generators.

Problems: Expensive to build. Flooding land and building dams cause environmental damage.

Tidal energy: Similar to hydroelectric energy, the lake fills when the tide comes in and empties when it goes out.

Problems: Similar to hydroelectric energy.

Wind energy: Generators are driven by wind turbines (windmills).

Problems: Large, remote, windy sites are needed. Winds are variable. The wind turbines are noisy and can spoil the landscape.

Wave energy: Generators driven by the up-and-down motion of waves at sea.

Problems: Difficult to build. Few devices have been successful.

Geothermal energy: Water is pumped down to hot rocks deep underground and rises as steam.

Problems: Deep drilling is difficult and expensive.

Solar energy: Solar panels absorb energy radiated from the Sun and use it to heat water.

Problems: Solar cells are expensive. Variable sunshine in some countries.

Biofuels: Made from plant/ animal batter. E.g. wood, alcohol <- sugarcane, methane gas <- rotting waste.

Problems: Huge areas of land are needed to grow plants.

 

Absolute Scales	Absolute Zero	Melting Ice	Boiling Water
Celsius	-273.15	0	100
Fahrenheit	-459.67	32	212
Kelvin	0	273	373

Kelvin = Celsius + 273

Fahrenheit = (1.8 x Celsius) + 32

 

Planets:	Mercury	Venus	Earth	Mars	Jupiter	Saturn	Uranus	Neptune
d from sun/million km	58	108	150	228	778	1420	2870	4490
t for 1 orbit/years	0.24	0.62	1	1.86	11.86	29.46	84.01	164.8
diameter/km	4880	12100	12800	6790	142980	120540	51120	49530
mass	0.06	0.82	1	0.11	318	95.2	14.5	17.2
Gravity field strength(N/kg)	3.8	8.8	9.8	3.8	25	10.4	10.4	13.8
density/g/cm3	5.4	5.2	5.5	3.9	1.3	0.7	1.3	1.6
Surface temperature/°C	170	460	15	-23	-110	-140	-210	-200
Moons	0	0	1	2	79	82	27	4