p711
Member
- Joined
- Apr 30, 2023
- Messages
- 20
- Gender
- Male
- HSC
- 2023
cuz its change in energy so its final - initialso what do I sub in for r in U? 6800km or 42000km
cuz its change in energy so its final - initialso what do I sub in for r in U? 6800km or 42000km
BOTHHH.so what do I sub in for r in U? 6800km or 42000km
ur logic is right but maybe u subbed in wrong or calculated wrong. i got A nowbut what i don't understand about using total energy is when you do final - initial u will get half of the answer ? (unless im doing sum wrong i do believe the right way is to do uf-ui) coz, when u do -gmm/2r(final) - (-gmm/2r(initial) you will get -gmm/2r(final) + gmm/2r(inital) which is half of answer a? can someone like legit go through the steps cause im bugging i think
damn bro relax thanks for ur help i understand nowBOTHHH.
∆E=1/2Uf-1/2Ui
=-GMm/2rf - (-GMm/2ri)
∆E=-(6.67x10^-11x1000x6.0x10^23)/(2x42000x10^3)-(-6.67x10^-11x1000x6x10^24)/(2x6800x10^3)but what i don't understand about using total energy is when you do final - initial u will get half of the answer ? (unless im doing sum wrong i do believe the right way is to do uf-ui) coz, when u do -gmm/2r(final) - (-gmm/2r(initial) you will get -gmm/2r(final) + gmm/2r(inital) which is half of answer a? can someone like legit go through the steps cause im bugging i think
You only use that when they ask for work done. In this case, the change in energy refers to change in TOTAL energycant u just use Ufinal - Uinitial? I did that and got the same answer A
so we dont add radius of the earth? otherwise then i agree the answer is a.∆E=-(6.67x10^-11x1000x6.0x10^23)/(2x42000x10^3)-(-6.67x10^-11x1000x6x10^24)/(2x6800x10^3)
=the answer in A cant be bothered seeing what it was
The question states radius, not altitude so you don’t have to add itso we dont add radius of the earth? otherwise then i agree the answer is a.
no because the radius is from the centre of the earth. when it says altitude that's when u add radiusso we dont add radius of the earth? otherwise then i agree the answer is a.
yea thanks for the helpYou only use that when they ask for work done. In this case, the change in energy refers to change in TOTAL energy
I wouldn’t risk it since the data sheet has 9.8 on itIf i were to use 9.81 for acceleration due to gravity instead of 9.8 will they care??
I mean on the reference sheet it says 9.8 so maybe just use thatIf i were to use 9.81 for acceleration due to gravity instead of 9.8 will they care??
whats the pointIf i were to use 9.81 for acceleration due to gravity instead of 9.8 will they care??
because it generally is the more used value out of the twowhats the point
the hsc syllabus uses 9.8, so you use 9.8. if they wanted you to use 9.81 they'd give you 9.81because it generally is the more used value out of the two