Barry Feierman, Westtown School, West Chester, PA, came up with a unique demonstration of Newton’s third law with a buoyancy experiment.
He uses a Force Plate to measure the weight (downward force) of a large beaker of water. He lowers a can of soup, suspended from a Dual-Range Force Sensor, into the beaker. How does the change in apparent weight of the soup can compare with the change in downward force on the Force Plate? What do you get when you graph the sum of the two force sensor readings?