Drop Them Both! UFLI Foundations Lesson 79
Practice Words
Max sits on a hill, holding a rock and a soft white feather. 'I will drop them both,' he says. 'The rock will hit the grass before the feather.' But does it have a lot more mass, or just a bit?
The rock is dark, solid, and sharp. Even the strong grip of the elephant can not chip it. In the harsh sun, the rock is hard, just as strong as before. Try biting one. No. Do not do that.
'A rock is a lot like an elephant,' says Max. 'Both are hard to move.' Max shoves hard at the elephant with both arms. He shoves and shoves, but the elephant does not budge at all. 'It wins,' Max puffs.
The elephant walks off. Max holds up the rock and the feather. The rock pulls his arm, but the soft feather would drift off in a gust. 'One of you is a grumpy lump,' Max says.
Max lifts the rock and gazes hard at it. That dark stone has a secret mass locked inside. 'What is your mass?' he asks. 'Five? Ten? Forty?' The rock says nothing. You can not tell the mass just by picking it up. Max must get help.
'Dad!' Max yells. 'I must find the mass of this rock!' Dad comes up the drive with his scale and a big grin. 'A scale is just the thing for this job!' he says. At last they can find the mass.
Dad holds up a flask of water. 'This flask, full to the top, is one,' he says. 'One flask, one mass.' He marks it on his chart with a grin.
'Dad, does more of something give more mass?' Max asks. 'Not at all!' says Dad. 'Ten cattle on this side of a large scale. Two hundred dogs on that side. Which side falls?' 'The dogs!' says Max. 'Wrong!' says Dad. 'The cattle win. It is not the sum that sets mass. It is what is packed inside.'
Max looks at the hills, the sky, the vast planet under him. 'Can we find the mass of the planet?' he asks. Dad smiles. 'No scale is that large. But math can find it.' Max blinks. Math can find the mass of it all?
'The mass of this planet is the same as jugs and jugs of water,' says Dad. 'More jugs than we can count!' Max can not take it all in. The sum is so big it can not fit on one chart.
'Can my feather match the flask?' Max asks. They pile up feathers until the stack rises far past the top of the scale. Then both pans sit still. The same mass. But one side is huge and one side is tiny.
Small drops start to fall from the sky. One lands on Max's arm, so tiny he can hardly feel it. 'But more and more drops form a large dark pond,' he says. Tiny things add up. Even a soft thing has mass.
Max gets on the scale. He is not as big as an elephant, but not as small as a melon. He sits with the rock and the feather beside him, just like before on the hill. 'One, two, drop!' he says. Which one do you think lands last? Go and try it!
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