SAT Subject Physics Practice Question 324: Answer and Explanation
20. A goldfish swims through an aquarium by moving its fins and tail. What causes the fish to move forward?
I. The force the water exerts on the goldfish
II. The force the tail of the goldfish exerts on the water
III. The force the fins of the goldfish exert on the water.
A. I only
B. II only
C. I and III only
D. II and III only
E. I, II, and III
Correct Answer: E
The correct answer is (E). The goldfish is pushed along by the water as a part of the action-reaction force pair as stated in Newton's Third Law.