I doubt it would loose you marks either way.

Bob

]]>I had thought that maybe the answer book was giving a simplified answer, it's an old A-level book, but the syllabus was very different back then, so I'm never sure what I'm expected to know But looking at it, if I draw a graph, I don't think *T* can ever - on this graph - be above *N* on the *y*-axis, so - presumably - the distance can always be given by *N* - *T*, with no need to worry about what would happen if *T* were to occur above *N*, giving a negative distance?

Because it is measuring distance and that cannot be negative. Without the || some values of t would give negative values for 4t^2 - 4t/3

Bob

]]>And after some mathematics, I come up with the solution that the length *l* of *NT* is:

Which agrees with the answer book, except the answer book does not have the modulus sign. I just wanted to clear-up why I can simply get rid of the modulus signs in this case, since my rustiness even extends to calculations of distance

]]>{7/3} and anonimnystefy, you're absolutely right. We know that *h* varies with *t*, specifically, it varies at the uniform rate of:

(As the question tells us.)

And we know that *V* varies with *h*, specifically, it varies at a rate of:

(According to my calculations)

We know, then, that *V* also varies with *t*, since it varies with *h*, which varies with *t*. Specifically, by the chain rule, it varies at a rate of:

Rate is usually taken as wrt time. So asking for dV/dt

Also look at the units for the book answer.

This is what Au101 has done.

Bob

]]>Welcome back; nice to hear from you again.

I've read and re-read this problem and I cannot find anything wrong with your answer. Maybe the book answer is just a typo. It would be easy to type two 1s rather than two zeros. My brain to finger coordination does this to me all the time. With the answer expressed as a multiple of pi it's hard to see why 110 (not divisible be 4) would be correct.

Bob

]]>So, does anyone know where I've gone wrong?

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