3000 J of heat is added to a system while 2000 J of work is done on the system. What is the change in Internal energy

The speed of light in a material is 0.50 c. what is the critical angle of a light ray at the interface between the material and a vacuum?

Ms.hidalgo opens the door to her classroom. her classroom is 60 degrees and the air outside is 80. predict what will happen using your knowledge of how heat flows.

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.