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Science Launch G5 / Week 05 / Wednesday
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Week 05 · Gravity Pulls Down

Wednesday

Investigation: The drop test
// Earth pulls everything toward its center
⏱ about 15 min

Wednesday: Investigation: The drop test

Raven holds two sheets of paper, exactly the same. Rocket watches, puzzled.

She crumples one sheet into a tight ball. The other stays flat.

"Same paper, same weight," she says. "If I drop them together, which lands first?"

Rocket answers fast. "Same weight, so they tie!"

Nova hums. "Interesting guess," she says. "What else is in the room that could push back on a falling sheet?"

What you need

  • Two sheets of the same paper
  • A piece of string about as long as your arm
  • A small object to tie on the string, like a key or a metal washer
Safety first
Drop only paper. Never drop anything heavy.
Stand on the floor, not on a chair or table.
Keep the area clear of people and pets.

Steps

  1. Tie the key to the end of the string.
  2. Hold the string up and let the key hang still. This is a plumb line.
  3. Notice the direction the string points. That is "down" toward Earth's center.
  4. Crumple one sheet of paper into a tight ball. Keep the other sheet flat.
  5. Make your prediction below.
  6. Hold both papers at the same height. Let go at the same moment.
  7. Repeat three times and watch which lands first.
MAKE A PREDICTION
  • Read the question.
  • Tap your answer.
Which paper do you predict will land first?
DropWhich landed first?
1
2
3

Gravity pulls both papers down toward Earth's center. They weigh the same.

But air pushes up against falling objects. That push is called air resistance.

The flat sheet has more surface for the air to push on, so it falls more slowly.

What slowed down the flat sheet? Type two words.
WHY THIS EXERCISEGravity pulled both sheets equally, but air pushed harder on the flat one and slowed it.

Gravity versus air

Gravity pulled both papers down with the same pull.

Air pushed up harder on the flat sheet because it had more surface.

So the crumpled ball usually wins the race.

DROP TEST THINKING
  • Read the question.
  • Tap your answer.
What does a plumb line show?
Why did we repeat the drop three times?
StatementTrue or false?
Air pushes up against falling objects.?
The flat and crumpled sheets weigh the same.?
The flat sheet has less surface for air to push on.?
WHY THIS EXERCISEMore surface means more air resistance, so the flat sheet falls slower.

You tested gravity and found a second force at work. Tomorrow we will travel to a place with no air at all.

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