I have a couple of science questions that I'm stuck on. Help..?
1. Describe how sound is created and gets to our ear for us to hear. Does sound need a medium to travel through?
2.What is wavelength? What does it tell us about the energy of a wave?
3.What is amplitude? What does it tell us about the energy of a wave?
4.What type of waves are light waves? Does light need a medium to travel through?

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.