QUIZ 2

46. 2*k*(lambda)*L/[x*(L² + 4x²)^1/2 ], perpendicular to the rod.

48. 2*k*Q*a/(x² + a²)^3/2.

62. (a) 1.1X10^-28C*m (b) 2.4X10^-24C*m (c) 1.7X10^-24C*m (d) 4.8X10^-24C*m

80. 4.9X10^-6 C; this value is expected to be small, since it does not take much charge to counteract the gravitational force. The electric force is more potent that the gravitational force, so relatively little charge is needed to maintain equilibrium. This goes to why the Empire State Building can stand and stay together despite what we perceive as large gravitational forces. This also explains why you do not go through the ground when you stand up. The normal force is a huge electrostatic repulsion over a small area under your feet acting against the gravitational force (your weight) of the entire Earth on you.

86. (a) 2*k*(lambda)/r, away from the rod. (b) 2.1X 10⁷ m/s.