Stairways are a form of?

Matt is driving down 7th street. he drives 150 meters in 18 seconds. assuming he does not speed up or slow down, what is his speed?

Light from the sun reaches the earth in 8.3 minutes. the velocity is 3.00 x 10^8 m/s. how far is earth from the sun? i know how to get to d = (3 x 10^8 m/s)(498 sec). i just don't know how to get from there to the answer being 1.5 x 10^11 m.

Matter is needed to transfer thermal energy bya. conductionb. convectionc. radiation d. both a & b.