When Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard, the speed of the skateboard
A) decreases.
B) increases.
C) neither decreases nor increases.
Question 2
Which of these problems arise partly from coal-fired power plants but not from nuclear power plants?
A) global warming
B) acid rain
C) Both of the above.
D) nuclear weapons proliferation
E) All of the above.