Two children push on opposite sides of a door during play. both push horizontally and perpendicular to the door. one child pushes with a force of 185 n at a distance of 0.500 m from the hinges, and the second pushes at a distance of 0.450 m. what force (in n) must the second exert to keep the door from moving? assume friction is negligible.

Auniform electric field exists in the region between two oppositely charged plane parallel plates separated by a distance of 1.60 cm . a proton is released from rest at the surface of the positively charged plate and strikes the surface of the opposite plate in a time interval of 3.20×10-6 s. 1-find the magnitude of the electric field. use 1.60×10-19c for the magnitude of the charge on an electron and 1.67×10-27kg for the mass of a proton 2-find the speed of the proton when it strikes the negatively charged plate