Ameter stick balances at the 50.0-cm mark. if a mass of 50.0 g is placed at the 90.0-cm mark, the stick balances at the 61.3-cm mark. what is the mass of the meter stick?

Ahuge (essentially infinite) horizontal nonconducting sheet 10.0 cm thick has charge uniformly spread over both faces. the upper face carries +95.0 nc/m2 while the lower face carries -25.0 nc/ m2. what is the magnitude of the electric field at a point within the sheet 2.00 cm below the upper face? (ε0 = 8.85 × 10-12 c2/n · m2)