2nd Law Examples!

Always write the 2nd Law in component form, after setting up coordinate axes, so that you have expressions like ΣFx = max. You can't do algebra with vectors, so you need component equations as your starting point to solve for unknowns. Example: ma = mg sinθ, 0 = n − mg cosθ, if no friction.


ma = T sin θ, 0 = mg − T cosθ, where θ is the angle the string makes with the vertical.
CONICAL PENDULUM



ma = n sinθ, n cosθ = mg.
if no friction.

A bucket swung in a vertical circle is a very educational 2nd Law problem!  Consider the net force acting on anything in the bucket, at each point on the circular path!


KINETIC AND STATIC FRICTION.  fk = μkn  and  0 ≤ fs ≤ μsn.





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