Mechanics (1 Viewer)

[Valentino25]

Mechanics is bumming me out, I'm just not getting it well.
I got most of the other topics down, its just this one. Any tips in general on how to go well in mechanics?
I may just be the way my teacher taught it, my whole class doesn't get it.
So yeah any general tips would be sweet! Thanks.

 

[bloodvial]

Try and establish a bit of a procedure, usually the trick is to find acceleration in terms of a rate of change of the variable you're trying to find over the variable you're given (usually v).

All you really need to remember is a =dv/dt = v dv/dx = d/dx (1/2 v^2) = d^2x/dt^2

For example if you're given/end up with after resolving forces a=(-mg+kv^2)/m and want to find an expression for velocity in terms of time you'd use dv/dt.

dv/dt = (-mg+kv^2)/m

dt/dv = m/2kv * 2kv/(-mg+kv^2)

t = m/2kv ln(-mg+kv^2) +c

etc.

Hope this helps. (I really need to learn LaTeX...)

 

[Sindivyn]

Just to add to bloodvial, integrating with limits saves ALOT of working (no need to find C). Just depends on the question.

 

[bloodvial]

Yeah, I see that in solutions all the time but our teacher never showed us how that works, looks a lot quicker. How do you do that?