derp (1 Viewer)

[elbatiolpxeho]

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I'm having an issue with part (iv) (2), this is Terry Lee's answer:

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Now the question is asking for the time taken to return to the surface, equating with D would yield the time taken to reach the maximum height but not the time taken for the whole journey (which would be twice the result due to the law of conservation of energy).

My approach was to simply equate the formula in part (iii) with R as it would yield the times at which the particle was at the surface, i.e.





This is twice the answer given by Terry Lee, as predicted.

What did I do wrong?

 

[funnytomato]

i did exactly what u did

i guess u just have to interpret the quesiton as the time for it to fall back from distance D, as stated in "iv) if ... reaches a point... and then falls back" , and both i) and ii) are under part iv)

if it used "fall" instead of "return", i guess it would make it a bit less ambiguous

the terry lee solution is only the time taken to reach point D, then it's gonna take the same amout time for it to fall back as you said , or you could subtract it from the total time to verify it

 

[elbatiolpxeho]

Thanks.