Why is lightning visible before thunder is heard?
A
Sound cannot reflect off surfaces as easily as light.

B
Sound travels slower than light can travel.

C
Sound is not processed by the brain as fast as light.

D
Sound needs a medium to travel through.

First answer marked as brainiest which is the correct equation describing the first law of thermodynamics? a) when the internal energy of a system changes, it equals the amount of heat added plus the work done. b) when work is done by the piston, it is equal to the heat added plus the change in internal energy of the system. c) when heat is added to the system, it is equal to the amount of work done by the piston plus the change in internal energy of the system.