A man pulled a 25.0 kg object 14.0 cm vertically with his teeth. (a) How much work (in J) was done on the object by the man in this lift, assuming the object was lifted at constant velocity? (Include the sign of the value in your answer.)

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.