One Law, Two Costumes

You'll learnto tell mass from weight, and see why a scale reads the push-back, not gravity.

Gravity is a single rule — masses pull, inverse-square in the distance. Up close it dresses down to mg; a scale never reads it directly. One student, one unchanging 60 kg, and five very different scale readings.

8 STEPS · 6 QUICK CHECKS · g = 10 m/s² · v5

GRAVITY LAB

Before you start

What you're looking at

A 60 kg student standing on a bathroom scale on Earth, beside a far-view panel of a test mass at distance r from a planet.

The question

What does the scale read in each place, and which number never changes anywhere?

Watch for

Watch the mass stay fixed at 60 kg while the scale reading changes from place to place.

What the symbols mean

Three readouts: mass in kilograms, gravitational force in newtons, and the scale display, which shows the upward push-back.

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