Buoyancy · Alberta Grade 5 · maddyhelps.com
Predict, then test in a sink or a bucket. The last two pairs are the interesting ones: the same stuff, a different result.
| Object | I predict | Floats | Sinks |
|---|---|---|---|
| An apple | |||
| A potato | |||
| An orange with its peel | |||
| The same orange, peeled | |||
| An ice cube | |||
| A coin | |||
| A ball of modelling clay | |||
| The same clay, shaped into a boat |
Why does the clay boat float when the clay ball sinks?
Float or sink?
Usually: the apple, the orange with its peel, the ice cube and the clay boat float; the potato, the peeled orange, the coin and the clay ball sink. The orange peel is full of tiny air pockets. The clay boat pushes aside much more water than the ball, so the water pushes up on it harder — the buoyant force — even though the clay weighs the same.
Results can vary — some potatoes float in salty or very cold water — and that is a good thing to see. A result that differs from the prediction is data, not a mistake.
Why this matters is on the looking closely page. More sheets