A popular claim reads, “When a canoeist pushes water backward with a paddle
PHYSICS · Multi-part · A Level · Physics · Mechanics and materials · Mechanics and materials
Problem
A popular claim reads, “When a canoeist pushes water backward with a paddle, the water pushes the paddle forward with an equal and opposite force, so these forces cancel and the canoe cannot move.”
(1) Identify the action–reaction force pair present when the paddle interacts with the water.
(2) Using separate verbal free-body descriptions for the water and for the canoe–paddler system, explain why the statement in the claim is incorrect.
(3) Describe qualitatively how the canoe’s acceleration would change if the paddler exerts the same backward force on the water while the canoe’s total mass is doubled (for example, by adding passengers), assuming water resistance remains negligible.