Roll On

To roll a boulder down a hill, you first have to get it over a 1-meter-high barrier. The "activation energy" required to roll it down the hill is ___.

Answers are

a) the force necessary to lift it one meter

b) dependent upon how far down the hill it will roll

c) the force necessary to lift it two meters

d) the energy needed to lift it two meters

e) the energy needed to lift it one meter

The final answer.