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#1 2014-01-17 10:00:55

ninjaman
Member
Registered: 2013-10-15
Posts: 42

second and third order derivatives

hello
I have this question and given my answer for second and third derivatives. not sure if its right though

View Image: CodeCogsEqn.gif

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#2 2014-01-17 10:33:30

bob bundy
Moderator
Registered: 2010-06-20
Posts: 6,428

Re: second and third order derivatives

hi ninjaman

Your image is somewhat squashed up and with no equals.  The dy should be ds.  This is what I think you meant:

This is correct

This first term is correct but the second bit is not.

But this is not right.  The sign is wrong and there shouldn't be a 3 there.

And this has gone completely wrong.  You've lost the 3 from the first term and the error above has made the second term wrong too.

I suggest you have a go at d2s/dt^2 again and I'll check again.

Bob


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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#3 2014-01-17 11:44:59

ninjaman
Member
Registered: 2013-10-15
Posts: 42

Re: second and third order derivatives

d^2s/dt = -3sint - cost

d^3s/dt = -3cost - - sint = -3cost +sint

if this isn't right I don't know what is.

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#4 2014-01-17 21:14:36

bob bundy
Moderator
Registered: 2010-06-20
Posts: 6,428

Re: second and third order derivatives

hi ninjaman

That's exactly right.  Well done!  smile

Bob


You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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