A square raft with edge length L = 2.4 m floats on a pond. You step on the raft, then dive off, and it oscillates up and down in simple harmonic motion at a frequency of f = 0.65 Hz. Enter an expression for the mass of the raft in terms of L, g, ρ, f, and π.

Point charges q1=+2.00μc and q2=−2.00μc are placed at adjacent corners of a square for which the length of each side is 1.50 cm . point a is at the center of the square, and point b is at the empty corner closest to q2. take the electric potential to be zero at a distance far from both charges. part a what is the electric potential at point a due to q1 and q2? express your answer with the appropriate units.