Buoyancy Activities

  1. Floating block
  1. Find the mass of the block of wood.
  1. Find the mass of the beaker of water (without the block)
  1. After removing the beaker from the scale, place the block in the water. Estimate how much of its volume is below the water surface.
  1. Predict what the scale will read when you find the mass of the beaker of water with the block floating in it.
  1. Find this mass, and compare it to your prediction.
  1. What, if anything, have you learned?

  1. Two floating blocks
  2. Take the small block of wood and place it in the beaker of water. Estimate how much of its volume is below the water surface.
  1. Estimate how much larger the larger block of wood is, compared to the smaller block.
  1. Predict what will happen when you place the larger block of wood into the beaker.
  1. Were you correct? Does this tell you anything about what the upward buoyant force exerted by the water on the block depends on?
  1. Push the smaller block further under water and then let go. What happens? Is this consistent with your conclusions above?
  1. Pull up a bit on the smaller block so it sits a little higher in the water and then let it go. What happens? Is this consistent with your conclusions above?
  1. Sketch a free-body diagram for one of the blocks. How does the buoyant force compare to the force of gravity exerted on the block by the Earth?
  1. An aluminum cylinder and a block of wood.
  2. Find the mass of the aluminum cylinder.
  1. Place the cylinder in the beaker of water. What happens?
  1. Find the mass of the block of wood. How does it compare to the mass of the aluminum?
  1. Predict what will happen when you place the wood into the beaker.
  1. Is your prediction correct? What, if anything, can you conclude from this?
  1. Bonus questions: determine the density of the aluminum cylinder and the block of wood.
  1. A ball of clay
  2. What happens when you take a ball of clay and place it in a beaker of water?
  1. Can you take the same ball of clay and make it float in the water? Describe how you might go about this, and then see if you are successful.
  1. What, if anything, do you learn from this?
  1. Adding mineral oil
  2. Take an ice cube and place it in mineral oil. Does it float or sink? Why?
  1. Now place the ice cube in water (this should be colored with food coloring). Does it float or sink? Why?
  1. Predict what would happen to the ball if you added mineral oil to the beaker with the ball and water. Do you think the ball will rise, fall, or stay at the same level?
  1. Add the mineral oil to the beaker. Were you right? How can you explain this?

  1. Three blocks and an overflow can
  2. Note that for each situation here you need to make sure the water level in the overflow can is up to the spout, and the catch bucket is in place, before you add a block to the container.
  1. Add the blocks, one by one, to the overflow can, and fill out the table below:

Block / Mass of block / Volume of block / Mass of water / Volume of water
  1. Note whether the block sinks or floats. What, if anything, can you conclude based on the results in the table above? You may want to conclude something for floating objects and something different for an object that sinks.