Bowling Balls: Will they Sink or Will they Float?
Students will investigate what determines whether a material will sink or float. They will be given a bowling ball and have to make measurements and conclusions on whether their bowling ball will float, hover, or sink when placed in an aquarium.
Vocabulary Words: Density (most will "know" this, but this will be an application)
Significant Figures, Buoyancy
Context for Use
Resource Type: Activities:Lab Activity
Grade Level: High School (9-12)
Description and Teaching Materials
Students should be divided into groups as small as possible to place more responsibility on each member. Group size is dependent on the number of bowling balls available to measure. Provide students with meter sticks, string, and a scale capable of measuring the weight or mass of the bowling balls. Give the students the challenge of determining whether their bowling ball will float or sink. Depending on teaching style, buoyant force and density can be discussed at this time or possibly later.
Students need to choose a bowling ball and then determine what the density of the ball is. Students should be encouraged to find the range of possible densities that the bowling ball could have, using the uncertainty of measurement in the ruler and scale. After students have reached their conclusion, have them place their data on the board in front. Have an aquarium filled ¾ with water (place a piece of foam on the bottom of the aquarium). Call the lab groups up one at a time and let them explain whether their bowling ball will sink or float and how they can justify their conclusion.
Teaching Notes and Tips
Bowling balls less than 12 lbs will float. Bowling balls greater than 12 lbs will sink. Bowling balls that are marked 12 lbs have a density very close to 1 g/mL and will sink, hover, or float. Give the 12 lb ball to the advanced group. Give the 6 and 16 pound balls to the groups who need the best chances of success.
Densities of other liquids can be found at: http://www.simetric.co.uk/si_liquids.htm
Areas of confusion for students include misconceptions about the terms density and weight.
A test question that evaluates if students can apply the knowledge gained from this lab experience is:
Explain why an iron nail sinks when dropped in water but a ship made of iron can float.