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# Mechanics Help!

Maths and statistics discussion, revision, exam and homework help.

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1. Mechanics Help!
Hi, I've got stuck on a mechanics question and I was wondering if anyone would be able to help at all?

First of all I do some work with Newton's second law of motion to get the [simple] differential equations d^2x/dt^2=2 and d^2y/dt^2=3x^2. We're told that the particle starts at rest at the origin at t=0.

The problem is that I have to show that the equation of the trajectory of the particle is y=x^3/10 but I seem to have computed that y=3x^3/2. Anyone know what I've done wrong?
2. Re: Mechanics Help!
3. Re: Mechanics Help!
(Original post by mthpossom)
Hi, I've got stuck on a mechanics question and I was wondering if anyone would be able to help at all?

First of all I do some work with Newton's second law of motion to get the [simple] differential equations d^2x/dt^2=2 and d^2y/dt^2=3x^2. We're told that the particle starts at rest at the origin at t=0.

The problem is that I have to show that the equation of the trajectory of the particle is y=x^3/10 but I seem to have computed that y=3x^3/2. Anyone know what I've done wrong?
You've treated x as a constant and not a function of t. Solve to find x in t and substitute into the second.
4. Re: Mechanics Help!
Thank you very much, I can do it now!

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