Competency #4
Answer and Explanation
The correct answer is D.
The only piece of information that we start with is that both objects are floating.
For this to be true, the buoyant force must be equal in magnitude to the weight of the object (in opposite directions, so that the net force is zero).
Force of gravity depends on mass of the objects, which we are not given. So there are three possibilities: the boat weighs more than the ducky, the ducky weighs more than the boat, or they have equal weights.
Let's draw a force diagram for each of these possibilities:
Which one is correct? We know that for floating objects, the object with the larger weight will have a greater buoyant force, but we don't know which one has a greater weight. Without more information there is no way to tell which one matches our situation. So we will have to choose answer D- need more information.