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AQA Mechanics 2 Unofficial Mark Scheme

Here are my answers from todays exam, not all of them will necessarily be correct so please correct me if you think they are wrong!
1. a) 9.6
b) i) 24.3
ii) 12.7
iii) No Air Resistance
2.
a) a=(84x3)i18e3xj a = (8-4x^3)i - 18e^{-3x}j
b) i) F=(168x3)i36e3xj F = (16-8x^3)i - 36e^{-3x}j
ii) 8.20
c) 1.26
d) r=(4x2x55+3)i(3+2e3x)j r = (4x^2- \frac{x^5}{5} + 3)i - (3+ 2e^{-3x})j
3. a) By symmetry
b)10.4 cm
c) 16.5 degrees
d) Explanation Q
4. a)78.4
b) 41.4 degrees
c) r=2.89
5. Lots of very long answers, will upload later if I have time. Part d) was sqrt(5gl) sqrt(5gl)
6. a) Show that Q
b) g(gλμ)etλλ \frac{g-(g-\lambda\mu)e^{-t\lambda} }{\lambda}
7. a) Diagram
b) tanx=12μ24μ tanx = \frac{1-2\mu^2}{4\mu}
8. 7.58m There have been lots of proposed answers for this question so not entirely sure if this is the correct one.
(edited 7 years ago)

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Original post by jjsnyder
Here are my answers from todays exam, not all of them will necessarily be correct so please correct me if you think they are wrong!
1. a) 9.6
b) i) 24.3
ii) 12.7
iii) No Air Resistance
2. Again long answers will fill in but the magnitude of F is 8.20
3. a) By symmetry
b)10.4 cm
c) 16.5 degrees
d) Explanation Q
4. a)78.4
b) 41.4 degrees
c) r=2.89
5. Lots of very long answers, will upload later if I have time. Part d) was root(5gl/2)
6. a) Show that Q
b) g(gλμ)etλλ \frac{g-(g-\lambda\mu)e^{-t\lambda} }{\lambda}
7. a) Diagram
b) tanx = (1-2mu^2)/4mu
8. a) 17.0
b) I got 6.05m but many others got 7.58m so this seems like the correct answer, can anyone confirm this?


I got the same for 7B) but without the m's
Reply 2
Did anyone get 2 rootlg?
Reply 3
Original post by ashwinderk
I got the same for 7B) but without the m's


No they are supposed to mean mu as in the greek letter μ \mu .Will edit now.
Reply 4
Original post by jjsnyder
No they are supposed to mean mu as in the greek letter μ \mu .Will edit now.


Where has the mu come from? for 6b
(edited 7 years ago)
Reply 5
Me
Original post by jjsnyder
Here are my answers from todays exam, not all of them will necessarily be correct so please correct me if you think they are wrong!
1. a) 9.6
b) i) 24.3
ii) 12.7
iii) No Air Resistance
2.
a) a=(84x3)i18e3xj a = (8-4x^3)i - 18e^{-3x}j
b) i) F=(168x3)i36e3xj F = (16-8x^3)i - 36e^{-3x}j
ii) 8.20
c) r=(4x2x55+3)i(3+2e3x)j r = (4x^2- \frac{x^5}{5} + 3)i - (3+ 2e^{-3x})j
3. a) By symmetry
b)10.4 cm
c) 16.5 degrees
d) Explanation Q
4. a)78.4
b) 41.4 degrees
c) r=2.89
5. Lots of very long answers, will upload later if I have time. Part d) was sqrt(5gl/2) sqrt(5gl/2)
6. a) Show that Q
b) g(gλμ)etλλ \frac{g-(g-\lambda\mu)e^{-t\lambda} }{\lambda}
7. a) Diagram
b) tanx = (1-2mu^2)/4mu
8. a) 17.0
b) I got 6.05m but many others got 7.58m so this seems like the correct answer, can anyone confirm this?

It was sqr(5gl) not sqr(5gl/2) because it was 1/2mu^2=1/2mv2+2mgl
Original post by MrMagic12345
It was sqr(5gl) not sqr(5gl/2) because it was 1/2mu^2=1/2mv2+2mgl


Yeah pretty sure it was 5gl\sqrt{5gl}. Q has come up before.
Reply 8
Original post by MrMagic12345
It was sqr(5gl) not sqr(5gl/2) because it was 1/2mu^2=1/2mv2+2mgl


How is not just 2 root lg?
Original post by jjsnyder
Here are my answers from todays exam, not all of them will necessarily be correct so please correct me if you think they are wrong!
1. a) 9.6
b) i) 24.3
ii) 12.7
iii) No Air Resistance
2.
a) a=(84x3)i18e3xj a = (8-4x^3)i - 18e^{-3x}j
b) i) F=(168x3)i36e3xj F = (16-8x^3)i - 36e^{-3x}j
ii) 8.20
c) r=(4x2x55+3)i(3+2e3x)j r = (4x^2- \frac{x^5}{5} + 3)i - (3+ 2e^{-3x})j
3. a) By symmetry
b)10.4 cm
c) 16.5 degrees
d) Explanation Q
4. a)78.4
b) 41.4 degrees
c) r=2.89
5. Lots of very long answers, will upload later if I have time. Part d) was sqrt(5gl/2) sqrt(5gl/2)
6. a) Show that Q
b) g(gλμ)etλλ \frac{g-(g-\lambda\mu)e^{-t\lambda} }{\lambda}
7. a) Diagram
b) tanx = (1-2mu^2)/4mu
8. a) 17.0
b) I got 6.05m but many others got 7.58m so this seems like the correct answer, can anyone confirm this?


I got for Q8 7.05 lol.

And because I'm full on retarded I did the whole of Q7 with μ\mu as the coefficient of friction for BOTH wall and floor. What an idiot, perfect method, 7 marks down the drain. I even read the 2μ2\mu after I finished the Q but apparently my brain has serious processing issues so I didn't register it.

Also 8. (a) and (b). Thought Q8 was just Q8, no parts?
(edited 7 years ago)
Reply 10
Original post by MrMagic12345
It was sqr(5gl) not sqr(5gl/2) because it was 1/2mu^2=1/2mv2+2mgl


Should be square root(4gl)


Posted from TSR Mobile
Original post by IrrationalRoot
Yeah pretty sure it was 5gl\sqrt{5gl}. Q has come up before.


I got this
Reply 12
Original post by MrMagic12345
It was sqr(5gl) not sqr(5gl/2) because it was 1/2mu^2=1/2mv2+2mgl


I got that
Reply 13
Original post by Yo12345
Should be square root(4gl)


Posted from TSR Mobile

Yeah it should be
Original post by Jm098
Did anyone get 2 rootlg?


No but I can see how you'd make that mistake. Note that yes, v must be positive (and real), but tension must be nonnegative too.
Original post by Jm098
How is not just 2 root lg?


Yessss boi same
Reply 16
What was the question 8a)
Original post by MrMagic12345
It was sqr(5gl) not sqr(5gl/2) because it was 1/2mu^2=1/2mv2+2mgl


agreed
Original post by IrrationalRoot
I got for Q8 7.05 lol.

And because I'm full on retarded I did the whole of Q7 with μ\mu as the coefficient of friction for BOTH wall and floor. What an idiot, perfect method, 7 marks down the drain. I even read the 2μ2\mu after I finished the Q but apparently my brain has serious processing issues so I didn't register it.

Also 8. (a) and (b). Thought Q8 was just Q8, no parts?


Question 8 was one part, 8 marker
Reply 19
Original post by IrrationalRoot
No but I can see how you'd make that mistake. Note that yes, v must be positive (and real), but tension must be nonnegative too.


No, tension was root(4gl) which simplified, was 2root(gl). Which gives non negative tension.


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