A sample learning object on the concept of buoyancy.

1. Physics 101 Learning Object 1:
Buoyancy Multiple Choice Question
Two beakers are filled with water to the same level and placed on a weighing scale. The
beaker on the left is just filled with water.
Q1.The beaker on the right contains a wooden ball that floats on the surface. Which weighing
scale reads a greater value: A) Left beaker, B) Right Beaker, C) Both beakers weigh the same
(circle one)?
Q2. The beaker on the right contains a metal ball that is held partially submerged by a
massless string attached to the ceiling. Which weighing scale reads a greater value: A) Left
beaker, B) Right Beaker, C) Both beakers weigh the same (circle one)?
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Ceiling

2. Physics 101 Learning Object 1:
Buoyancy Multiple Choice Question
Q1.The beaker on the right contains a wooden ball that floats on the surface. Which weighing
scale reads a greater value: Left beaker, Right Beaker, Both beakers weigh the same (circle
one)?
Answer: Both beakers weigh the same.
Explanation: The most important thing to note in this question is that the wooden ball is
floating on the surface of the water. This indicates that the weight of the water displaced by
the wooden ball is equivalent to the weight of the ball itself. Given that the water levels are the
same in both beakers (there is more water in the left beaker though), the weight of the ball
adds to the weight of the water in the right beaker - thus, the total weight of both beakers are
the same. The left beaker is full of water and the right beaker holds less water but contains a
ball.
Q2. The beaker on the right contains a metal ball that is held partially submerged by a
massless string attached to the ceiling. Which weighing scale reads a greater value:w
Left beaker, Right Beaker, Both beakers weigh the same (circle one)?
Answer: Both beakers weigh the same.
Explanation: This question actually has the same
explanation as the previous question with one notable
change: because the metal ball is suspended by the
ceiling, its weight is reduced because of the tension in
the string. The amount of water displaced by the
suspended metal ball contributes to the water level being
the same between the left and right beakers. From here
on, the explanation is the same as the previous question.
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Ceiling
TFB
Fg
FB
Fg