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**ninjaman****Member**- Registered: 2013-10-15
- Posts: 55

hello

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

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,736

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

Children are not defined by school ...........The Fonz

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

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**ninjaman****Member**- Registered: 2013-10-15
- Posts: 55

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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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 7,736

hi ninjaman

That's exactly right. Well done!

Bob

Children are not defined by school ...........The Fonz

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

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