Study for test
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11/01/2010 4:48pm

what is the formula for gpe?Do you

11/01/2010 5:12pm

ms. James for the ecology project can it only be one thing because i wanted to do it on reducing carbon footprint so can i do like recycling and other things on can it only be one thing

C James
11/01/2010 5:14pm

@ Scottie
GPE= mgh or GPE= wh
w= mg
g= 9.81 m/s^2

I am not sure if I understand, but yes your project can be only one thing

11/01/2010 5:45pm

Ms.james on ex. 6-3 how did you get 1.24

11/01/2010 5:58pm

[ms. james, on the other website(allaboutabearandabug) i comented saying, i dont know what topic/ so i will ask it here......] I dont have any other ideas for the ecology project? do you have any examples? and also, when is the journal entry due...?

C James
11/01/2010 7:06pm

How much mass energy, in joules, could be obtained from the complete conversion of a compact 138 g media player?
m= 138 g You have to convert to kg here
m= 0.138 kg
c= 3.00 x 10^8 m/s
since c is squared
c^2= 9 x 10^16 m^2/s^2
E= ?
E= mc^2
E= 0.138 kg (3.00 x 108 m/s)2
E= 0.138 kg (9 x 10^16 m^2/s^2)
E= 1.242 x 10^16 kg* m2/s2
E= 1.24 x 10^16 J

the carrot (^) indicates that you have to make the number that follows a superscript (10^16 means 10 to the 16th power)

Let me know if this helps

C James
11/01/2010 7:07pm

Ciara, there are many things to do. Talk to me in homeroom and I will give you some ideas. BTW the eco-blog is not for class questions, I want to keep it strictly eco-info

11/01/2010 7:26pm

ok ms.james after you got
what do you do because i dont
understand where you got 1.242

C James
11/01/2010 7:38pm

@Scottie, after you square c (3.0 x 10^8 m/s) you multiply it by 0.138 kg. that is 9 x 10^16 m^2/s^2

so you can actually just multiply 0.138 kg by 9 and you will get 1.24 then just add the x 10^16 m^2/s^2 and you will have 1.24 x 10^16 kg m^2/s^2

11/01/2010 7:41pm

how do u use e=mc2

11/01/2010 7:42pm

thanks ms.james

11/01/2010 7:44pm

Hey. Ms. J If we use the notes that you told us to write down will that suffice for the test or should we study the book and notes. My second question is what formulas do we have to know?

11/01/2010 7:44pm

can u give me an exampel and explan it

11/01/2010 7:59pm

ms.james can you please send me
2 examples of gpe and e=m2 so i can see
see if i get them correct

C James
11/01/2010 8:49pm

@ scottie you are welcome

Scottie and Jeremiah,
I have worked our some problems below. I will attach some problems to today's post.

How much gravitational potential energy has a boy whose mass is 50 kg and who is standing on top of a 1.5 meter high wall?

GPE= mgh
m= 50 kg
g= 9.81 m/s^2
h= 1.5 m
GPE= (50 kg)(9.81 m/s^2)(1.5 m)
GPE= 735.75 kg m^2/s^2
GPE= 735 J

How much energy would be generated if a physics student (mass = 62 kg) could be completely turned into energy?

E= mc^2
m= 62 kg
c= 3.0 x 10^8 m/s
c^2= 9.0 x 10^16 m^2/s^2
E= 62 kg(9.0 x10^16 m^2/s^2)
E= 558 x 10^16 k m^2/s^2
E= 558 x 10^16 J
E= 5.58 x10^18 J

11/02/2010 5:46pm

Hi,Mrs. James i wanted to know what was the homework was for today.


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