Which of the following statements is true about electric forces? a. electric forces cause objects to only attract each other. b. electric forces cause objects to only repel each other. c. electric forces cause objects to repel or attract each other. d. electric forces have no effect on each other.

Consider a 1000 w iron whose base plate is made of 0.5 cm thick aluminum alloy 2024-t6 (ρ = 2770 kg/m3 and cp = 875 j/kg°c). the base plate has a surface area of 0.03 m2. initially, the iron is in thermal equilibrium with the ambient air at 22°c. assuming 90% of the heat generated in the resistance wires is transferred to the plate, determine the minimum time needed for the plate temperature to reach 200°c.