Spinning

Purpose - To separate the suspended parts of a suspensionby spinning.

Materialshammer nail

1- lb. metal coffee can

3 feet (1 m) cotton twine tapwater

2 tablespoons (30 ml) flourclear drinking glass adult helper

Procedure

■ Ask an adult to use the hammer and nail to maketwo holes across from each other beneath the top rim of the can.

■ Tie the ends of the twine in these holes.

■ Fill the can Vz full withwater.

■ Stir the flour into the water.

■ Carry the can and the empty glass outside.

■ Hold the twine and swing the can around 15 times. CAUTION: Stand in an open area. Do not release the twine.

■ Pour a small amount of the liquid into the emptyglass. If it looks cloudy, swing 10 more times.

■ Continue to swing and testfor cloudiness until the liquid stops changing.

Results The solution clears.

Why? Themixture of the flour and water forms a suspension. Assoon as the stirring stops, the undissolved flour particles start settling tothe bottom of the can. Spinning the can produces a strong outward force. Thisforce pushes the suspended flour particles to the bottom of the can. Thus, spinning the can speeds the settling process.

Spinning