In: Physics
A horizontal disk with radius R and charge density σ is centered originally. A particle with charge Q and mass m is in equilibrium at a height h above the center of the plate, as shown. A gravitational field is present. R = 1.5 m σ = -5⋅10-7 C / m2 h = 2 m Q = -2 µC a) Calculate the mass m of the particle if it is at equilibrium (use g = 9.81 m / s2 ). b) Calculate the electric potentials created by the disc at the following two positions on the Y axis: at y = 2 m and at y = 4 m. c) If we remove the gravitational field, calculate how fast the particle will reach the position y = 4 m. d) In the absence of a gravitational field, calculate the external work required to bring the particle Q from infinity to the center of the disc (i.e. y = 0 m), without variation of speed. (Reminder: V∞ = 0)