Question

The total U.S. consumption of electricity in a particular year was 5.0 x 1012 kilowatt-hours. What is the mass equivalence of this amount of energy? Show all calculations leading to an answer.

Answer 1

5.0x10^12

Answer 2

@peachpi

Answer 3

Honestly, I've never seen this before, but I think you convert kW-h to J and use E = mc²

Answer 4

quite right ....just calculate the year's energy in joules and then use E=mc^2 to find out the mass equivalence ...

Answer 5

can you walk me through changing it to joules please

Answer 6

okay hold on

Answer 7

1 kilowatt hour =
3 600 000 joules

Answer 8

convert it your Kwh into joules then put it in E=MC^2

Answer 9

E being your energy in jouls ....and C being the speed of light

Answer 10

use SI units

Answer 11

so 5.0*10^12=5,000,000,000,000

Answer 12

now multiply it by 3 600 000

Answer 13

yu get your enerygy in jouls then

Answer 14

don t get rid of the exponantional notation here ...it help keeps the number small

Answer 15

so 1.8*10^19j

Answer 16

3 600 000 x (your enrgy in Kwh) = MC^2
you need to fing out M

Answer 17

J*

Answer 18

yeah ... there ya go ^_^

Answer 19

and than the equation i need is M=E/C^2

Answer 20

correct?

Answer 21

yes

Answer 22

good work

Answer 23

So M=1.8*10^19J/299792458m/s

Answer 24

gottta change m/s to J

Answer 25

Basically, the equation states that matter and energy are identical. If you could convert a small amount of matter completely, it would yield a tremendous amount of energy. in your case how ever you are finding the mass cause you already know the energy

Answer 26

everything should be in SI units ....like meter for distance jouls for energy ...

Answer 27

so what do i do than

Answer 28

So M=1.8*10^19J/299792458m/s you said this was your answer right ?

Answer 29

yes but isnt there something more i have to do

Answer 30

that figure is your answer .... express it in kilograms and your all set

Answer 31

how do i express it in kilograms

Answer 32

just do 1.8*10^19/299792458 and add the alphabets Kg in the end

Answer 33

would you believe it i am driving right now ....and i pull over to the side to answer your questions

Answer 34

are you clear on this ?

Answer 35

haha thank you so much

Answer 36

feel free to ask .... i am in the parking lot now

Answer 37

Would you help me with one more question if i post it

Answer 38

No problem bro

Answer 39

depends if i can solve it myself .... ... hit me with it