1. Two electrically charged pith balls, each having a mass of 0.15g are suspended from light threads of equal length. Determine the magnitude of the horizontal repulsive force, F, acting on each ball if the measured distance between them is r= 200mm. S0 mm- 150 mm 150 mm -F r- 200 mm 2. Determine the magnitude of P and the coordinate direction angles of F3 required for equilibrium of the particle. Note that F3 acts in the octant shown. (-1f.-7ft, 4 1) F-360 lb F-120 lb 20 F- 300 Ib F,= 200 lly

4. An electron is in motion at 4.0 × 106 m/s horizontally when it enters a region of space between two parallel plates, as shown, starting at the negative plate. The electron deflects downwards and strikes the bottom plate. The magnitude of the electric field between the plates is 4.0 × 102 N/C and separation between the charged plates is 2.0 cm. d = 2.0 cm a. Referring to the previous image, state the sign of the charge on each electric plate: i. Sign of bottom plate -. ii. Sign of the top plate -. b. Determine the acceleration of the electron between the plates. c. Determine the horizontal distance travelled by the electron when it hits the plate. d. Determine the velocity of the electron as it strikes the plate.

4. Consider the diagram. Find the position x of the mass m such that the system is horizontal and balanced. Also for what value of h would there exist no force of the pivot on the rod? The fulcrum is at the midpoint of the rod. There is only a force of gravity on the hanging mass, not on the rod or the charges. Ignore the two coulomb forces that are diagonal. X=? +2g tQ +Q

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Using the symmetry of the arrangement, determine the direction of the force on +q in the figure below, given that: Case I. qa=qb= +6.5 μC and qc = qd = +6.5 μC. (a) In your notebook, draw the forces on q due to qar qb²9c² (b) Due to symmetry the direction of the net force is F O qc net ✔N O qd Hint: For each force draw the x and y components. Some will add and some will cancel. (c) Calculate the magnitude of the force on the charge q, given that the square is 10.0 cm on a side and q = 2.3 μC. and 9d- X