Problem 1: you go outside on a hot, sunny summer day and you feel the warm sun on your skin. what causes this warmth?

a. the sun heats the air directly around your skin.

b. waves of light carry energy directly to your skin.

c. light causes surface waves on your skin.

d. water vapor in the air warms your skin.

problem 2: when a water wave runs into you at the beach, what causes you to get knocked down?

a. air molecules in front of the wave

b. the wave's energy

c. periodic motion

d. friction