Physics A-Level (Modelling Physics OCR Spec query)

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GigglingSquid319
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#1
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#1
Hi guys, I have literally been to the moon and back with this question and cannot seem to get a number anywhere near the four given ones. Does anyone have any insight on how to get the answer?

The specimen answers only contain the letter of the correct answer and no solution to getting there which is quite frustrating. Has anyone got the full solutions to the multiple choice for the new OCR Spec Papers?

Thank you!

"Scientists are planning to launch a rocket from the surface of the Earth into an orbit at a distance of 18000 km above the centre of the Earth. The radius of the Earth is 6400 km and it has mass 6.0 x 10^24 kg
What is the minimum work done to move the 150kg mass of the rocket into this orbit?"
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Eimmanuel
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#2
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#2
(Original post by leelasaeng)
Hi guys, I have literally been to the moon and back with this question and cannot seem to get a number anywhere near the four given ones. Does anyone have any insight on how to get the answer?

The specimen answers only contain the letter of the correct answer and no solution to getting there which is quite frustrating. Has anyone got the full solutions to the multiple choice for the new OCR Spec Papers?

Thank you!

"Scientists are planning to launch a rocket from the surface of the Earth into an orbit at a distance of 18000 km above the centre of the Earth. The radius of the Earth is 6400 km and it has mass 6.0 x 10^24 kg
What is the minimum work done to move the 150kg mass of the rocket into this orbit?"

Make use of the GPE formula and find the difference in GPE

 W = -\dfrac {GM_Em}{r_f} + \dfrac {GM_Em}{r_i}
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DrFaust
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#3
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I've been stuck on this question as well, done the paper a couple times and this one just doesn't seem to work. I used the same formula suggested Eimmanuel on several attempts, I can only get 6x10^9, still out by a 10^4. May just be doing something really stupid, but it's starting to look to me that the question might not be written correctly....
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Eimmanuel
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(Original post by DrFaust)
I've been stuck on this question as well, done the paper a couple times and this one just doesn't seem to work. I used the same formula suggested Eimmanuel on several attempts, I can only get 6x10^9, still out by a 10^4. May just be doing something really stupid, but it's starting to look to me that the question might not be written correctly....
I would agree that the order of magnitude of the choices is incorrect.
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GigglingSquid319
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#5
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(Original post by DrFaust)
I've been stuck on this question as well, done the paper a couple times and this one just doesn't seem to work. I used the same formula suggested Eimmanuel on several attempts, I can only get 6x10^9, still out by a 10^4. May just be doing something really stupid, but it's starting to look to me that the question might not be written correctly....
Likewise, I have also been getting that answer. Thank you both for clearing this up!
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FusionNetworks
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#6
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I also got 6x10^9.
They have likely messed up the multiple choice answers.
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richardhello
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leelasaeng I came across this question too, I couldn't find an answer either so guessed at C (which was right).

The only thing I could work out was that it had to be C or D due to the signs.
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Myles244
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#8
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If you access the paper through the OCR website they have updated the answers to the question, the correct answer is 7.7x10^9. Because you have GPE which is 6.04x10^9 and KE which is 1.68x10^9 which sum to 7.7x10^9, option B.

https://www.ocr.org.uk/Images/171727...-materials.pdf
Last edited by Myles244; 4 weeks ago
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