When exposed to air, white phosphorous immediately and rapidly reacts with oxygen. What can you say about the activation energy of this reaction?

If fine copper wool is heated in a crucible, it will react with oxygen in order to form copper (II) oxide. However at room temperature, the copper wool does not appear to react. Compare the activation energy of the copper and oxygen reaction to that of the phosphorous and oxygen reaction.

Two molecules move rapidly, but slow down as they get close to each other. What causes this drop in speed?