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Sports Physics 6-8 / Week 03 / Game Day
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Week 03 · Mass Matters

Game Day

Game Day: The push test
// The same push, a different result
⏱ about 20 min

Game Day: The Push Test

Saturday at the Field, a row of objects waits on the tape line. A foam ball, a tennis ball, a shoe, a loaded backpack.

"One push each, same hand, same strength," Rocket announces. "We measure how far each one goes."

Raven holds the tape measure. "Predict the order first. Lightest to heaviest, or farthest to shortest?"

A cousin picks up the backpack. "This one will not go anywhere." Rocket grins. "Push it and see."

Nova hovers above the line, flashing once for each push.

The foam ball sails. The shoe scoots. The backpack shifts a hand's width.

"What do you notice?" Raven asks. "Same push, and the order matched the masses almost exactly."

  1. Mass is the amount of matter in an object, measured in kilograms.
  2. The change in motion depends on the force and on the mass.
  3. A larger force on the same object makes a larger change. More mass with the same force makes a smaller change.
  4. Weight is the force of gravity on a mass, measured in newtons. It changes from Earth to the Moon.
  5. Mass does not change from place to place. One kilogram is one kilogram everywhere.
◇ FAMILY PUSH TEST
Line up four or five safe objects of different mass on a tape line: balls, a shoe, a book, a backpack.
Each person predicts the order from farthest to shortest slide after one gentle push.
One person gives each object the same gentle push with a flat hand. Measure how far each slides.
Compare the measured order with the predictions. Talk about which object surprised people.
Try lifting each object too. Talk about the difference between the pull you feel and the push you gave.
For a grown-up
Only soft, unbreakable objects are pushed, and only along the floor or grass. Nothing is thrown.
Keep the sliding lane clear of toes, pets and furniture. A grown-up moves anything heavy.
The mass and weight facts this week come from an OpenStax physics text, NASA and NIST, at openstax.org, nasa.gov and nist.gov.
Safety first
Push with a flat hand along the ground. Nothing is thrown or kicked at anyone.
Lift heavy things with your legs, or let a grown-up lift them.
Stop if anyone is tired or hurt.
THINK IT THROUGH
  • Read the question.
  • Tap your answer.
The same push moved the foam ball farthest and the backpack least. Which has the most mass?
If the backpack went to the Moon, what would stay the same?
Game Day checkTrue or false?
The same push gives a smaller change in motion to an object with more mass.?
Weight stays the same on the Moon.?
Mass is measured in kilograms.?
WHY THIS EXERCISEThe push test is Newton's second law lined up on a tape line.
Draw your line of objects after the push test, each at the distance it slid. Label them from least mass to most.
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