Saturday, October 02, 2010

Motion in One Dimension

I think it was about a week ago or so that I declared chapter two of University Physics, by Young and Freeman, dead.  I had been sauntering through it for months.  The main points are easy, although as usual the application of them into concrete situations is more diffiicult.  But here I summarize the main points:

1. Average velocity Δx/Δt or (x2-x1)/(t2-t1).

2. Instantaneous velocity is lim Δt→0 of Δx/Δt, which = dx/dt.

3. Average acceleration Δv/Δt or (v2-v1)/(t2-t1).

4. Instantaneous acceleration is lim Δt→0 of Δv/Δt, which = dv/dt.

Then these equations work for constant acceleration
5. v2 = v1 + at

6. x2 = x1 + vt + ½at2

7. v22 = v12 + 2a(x2-x1)

8. x2 - x1 = [(v2 + v1)/2]t

9. Finally, for varying acceleration, one will have to integrate:

x2 = x1 + ∫0→t of v dt

v2 = v1 +∫0→t of a dt

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