) Help with Physics question?

A sound wave traveling at 343 m/s takes 10.0 s to go from a speaker to a detector. How far apart are the two devices?
A.) 3.43 x 10^3
B.) 3.43 x 10^2
C.) 3.43 x 10^-1
D.) 3.43 x 10^4

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.