Typically the first bit of calculus one sees in physics is in kinematics. Namely, the question of how to find a position function given a constant acceleration, knowing that acceleration is the second derivative of the displacement (with the velocity being the second derivative). After that, you can use calculus to find the work done by a varying force, it can be used in potential energy calculations (particularly when dealing with Newtonian gravitation). But I'm not so sure calculus is used that often in an introductory course in physics. It is used to prove certain things or to derive equations, but students typically don't see that many problems actually involving calculus. There are a lot of free body diagrams and energy calculations, but calculus only shows up in the less-than-ideal problems.
An example of its use to derive something is, for example, the position function given a constant acceleration. Given [tex]\frac{d^2 s}{dt^2} = a[/tex] and the initial values [itex]s(0) = s_0[/itex] and [itex]s'(0) = v(0) = v_0[/itex], we can integrate twice to get [tex]s = \frac{1}{2}at^2 + v_0 t + s_0[/tex] But this is merely to derive the formula, and unless you really hate memorizing formulas, it's not typically done more than once.