How did we go in Exam 2?

[baddin]

Remember that question where they gave us dv/dt = -1/100 ( 145 - 3t^2) (or something close to that i dont remember). What values did you get for c. I had to choose between c = 25 and c = 417/50 (Something around there from memory)  and c = 25 didnt make sense for me. what c value did you pick?

[HighLatency]

I got n=-6 or n=6 as the angles have to be in the principle range. So that makes pi/2 and -pi/2.

So did you have to put the constant k anywhere because I said that it could be pi/2 + 2kpi and also n = -6,6 when in the principle range

[DJing]

Remember that question where they gave us dv/dt = -1/100 ( 145 - 3t^2) (or something close to that i dont remember). What values did you get for c. I had to choose between c = 25 and c = 417/50 (Something around there from memory)  and c = 25 didnt make sense for me. what c value did you pick?

c=25 as v=25 when t=0

[InsaneMcFries]

I chose c=25, also if I left my answers as cis(pi/2) and cis(-pi/2) would I lose marks?

[HighLatency]

Remember that question where they gave us dv/dt = -1/100 ( 145 - 3t^2) (or something close to that i dont remember). What values did you get for c. I had to choose between c = 25 and c = 417/50 (Something around there from memory)  and c = 25 didnt make sense for me. what c value did you pick?

c=25 as v=25 when t=0

was the next bit t=20 when v = 0?
The graph was a bit dodgy and I think i got it wrong...

[baddin]

Remember that question where they gave us dv/dt = -1/100 ( 145 - 3t^2) (or something close to that i dont remember). What values did you get for c. I had to choose between c = 25 and c = 417/50 (Something around there from memory)  and c = 25 didnt make sense for me. what c value did you pick?

c=25 as v=25 when t=0

But i dont think that satisfies when t = 139, v = 25 m/s

[DJing]

Remember that question where they gave us dv/dt = -1/100 ( 145 - 3t^2) (or something close to that i dont remember). What values did you get for c. I had to choose between c = 25 and c = 417/50 (Something around there from memory)  and c = 25 didnt make sense for me. what c value did you pick?

c=25 as v=25 when t=0

was the next bit t=20 when v = 0?
The graph was a bit dodgy and I think i got it wrong...

Yep, I think so, you couldn't really have it 'brake' twice, so the first instance was what I took to be correct

[DJing]

Remember that question where they gave us dv/dt = -1/100 ( 145 - 3t^2) (or something close to that i dont remember). What values did you get for c. I had to choose between c = 25 and c = 417/50 (Something around there from memory)  and c = 25 didnt make sense for me. what c value did you pick?

c=25 as v=25 when t=0

But i dont think that satisfies when t = 139, v = 25 m/s

t was t seconds after applying the brakes
T was T seconds from the start of motion

[9_7]

Remember that question where they gave us dv/dt = -1/100 ( 145 - 3t^2) (or something close to that i dont remember). What values did you get for c. I had to choose between c = 25 and c = 417/50 (Something around there from memory)  and c = 25 didnt make sense for me. what c value did you pick?

c=25 as v=25 when t=0

But i dont think that satisfies when t = 139, v = 25 m/s

t was the time in seconds* after the brakes applied

[Special At Specialist]

Remember that question where they gave us dv/dt = -1/100 ( 145 - 3t^2) (or something close to that i dont remember). What values did you get for c. I had to choose between c = 25 and c = 417/50 (Something around there from memory)  and c = 25 didnt make sense for me. what c value did you pick?

I said c = 25 and that's why I got no solution to the next question which asked for the time when it was at rest

[Oakleaf]

For the complex numbers question with finding n, I wrote n=6(2k-1), k is an element of Z, then said that this gave two unique solutions when k=0,1, the there would be two unique solutions when n=-6 and n=6. I then did the same as ZanyCat for the part after.

I thought that due to n being the power, the arg() could have been anything. The angle is usually restricted, but that would be converted in the final answer, not restricting the number of values for n. However, there were only two unique z1^n, where n satisfied the earlier condition. I think if you quoted any two for the second part, it would have been correct as long as they gave i and -i.

TL;DR: I agree with ZanyCat.

[Special At Specialist]

t was t seconds after applying the brakes
T was T seconds from the start of motion

Okay now I'm even less confident than I was before...

[Special At Specialist]

For the complex numbers question with finding n, I wrote n=6(2k-1), k is an element of Z, then said that this gave two unique solutions when k=0,1, the there would be two unique solutions when n=-6 and n=6. I then did the same as ZanyCat for the part after.

I thought that due to n being the power, the arg() could have been anything. The angle is usually restricted, but that would be converted in the final answer, not restricting the number of values for n. However, there were only two unique z1^n, where n satisfied the earlier condition. I think if you quoted any two for the second part, it would have been correct as long as they gave i and -i.

TL;DR: I agree with ZanyCat.

I said that the answers were i and -i, but I didn't give any restrictions on the value of n...

[DJing]

New Question:
For the expressions of distance traveled did you put

During stage 1: blahblah (with limits)
During stage 2 of motion: distance from 0-19 + 25*(T-19)
During stage 3: distance from 0-19 + 3000 + antiderivative of last stage? (with t)

[ZanyCat]

Stage 1 I put terminals with 'bla bla', stage 2 I put 120 * 25 (or whatever the values were) and stage 3 I had another integral with terminals :S

i.e. I interpreted it as the distance traveled in each stage, not the cumulative distance by the end of the stage.