Mechanics 2 Help :( Watch

CharlyMOO
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Report Thread starter 10 years ago
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I can't work out part (ii) on Question 2 on this link

http://www.meidistance.co.uk/pdf/m2eass.pdf

I don't quite know what to do to work out the acceleration of D

I got that the frictional force on the block was 22.52

A: T - 4g = 4a
Block: T - 22.52 - 5gsin40 = 5a
D: 15g - 15 = 15a

not sure if any of this is right tho Would be a big help thanks Then I will be able to work out the rest
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Maths Buster
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The tensions either side of the mass will be different. Your 2nd equation should therefore have T* and not T. Your 3rd equation is also missing -T*.
However, I think they were guiding you to use energy:
KE = 0.5[15]v^2 + 0.5[5]v^2 + 0.5[4]v^2 = 12 V^2.
Work done = -15[1.5] - 0.6[5gcos40]1.5 = -56.3.
Then use your 1st answer to get 12V^2 = 114 - 56.3, giving V = 2.2.
Use energy in part (c) too.
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CharlyMOO
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Thank you .. I just realised that energy was probably the best route to go in
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