ENERGY in our schoolEnergy is necessary for people or machines
to operate. A stretched spring has got energy. Food is a source of energy for living beings.
Chemical energy isn't stored only in food but also in petrol. Petrol contains suitable
form of energy for car motors with internal combustion. A pocket torch exploits the energy
for shining from batteries.
In the
middle of the past century physics progressively recognised the energy law to be a red
thread which totally links all pieces of physics. The law expresses the cognition which is
also useful outside physics and says that you can't get something from anything. You can
not see or touch energy. An observed body has got energy, just like an owner of a bank
account has property. Real property increases when the owner puts money into the bank and
drops, if he withdraws it. This is how the energy of the body increases, if the body
receives work or heat and drops when the body gives away the energy or the heat.
People need work and heat
(we usually say just energy) for living., we travel, lift objects, shine, cultivate
objects, heat the spaces etc.
Some interesting
information about energy
How much energy does it have? |
Energy (J) |
A
plane that flies with the speed of 900 km/h at a latitude of 1000m |
7 - 102 |
Amount of food that a grown man consumes in a in week |
107 |
A car that drives whit a speed of 100 km/h |
5 - 105 |
A drop of rain (one) |
4 - 10-5 |
|
Splošno
o ENERGIJIEnergija je potrebna, da ljudje ali pa stroji opravljajo določeno delo.
Energijo ima napeta vzmet. Hrana je vir energije za živa bitja. Kemična energija ni
spravljena samo v hrani , ampak tudi v bencinu. Ta vsebuje primerno obliko energije za
avtomobilske motorje na notranje izgorevanje. Tudi za razsvetljavo in gretje potrebujemo
energijo. Ročna svetilka črpa energijo iz baterij, da lahko sveti.
Sredi prejšnjega stoletja
so fiziki postopno spoznali energijski zakon, ki kot rdeča nit povezuje v celoto vse dele
fizike. Zakon izraža spoznanje, ki pogosto velja tudi zunaj fizike: nekaj ni mogoče
dobiti iz nič. Energije ni mogoče otipati ali naravnost opaziti. Energijo ima opazovano
telo, kot ima imetje lastnik bančnega računa. Imetje se poveča, če vloži gotovino in
zmanjša, če dvigne gotovino. Tako se energija telesa poveča, če telo delo ali toploto
prejme in zmanjša, če telo odda delo ali toploto.
Ljudje potrebujemo delo in
toploto (ponavadi rečemo kar energijo) za življenje: potujemo, dvigujemo bremena, si
svetimo, obdelujemo predmete, ogrevamo prostore, . . .
Nekaj zanimivih primerjav vrednosti energij
Koliko energije ima? |
Energija (J) |
letalo,
ki leti s hitrostjo 900 km/h na višini 1000 m |
7 - 102 |
količina
hrane, ki jo odrasel človek zaužije v enem tednu |
107 |
avto, ki
vozi s hitrostjo 100 km/h |
5 - 105 |
padajoča
dežna kaplja |
4 - 10-5 |
|