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MOTION · B1 · 005 · Apparent weight

You can't feel speed. You can only feel it changing.

Apparent weight: what you feel is how hard the floor pushes on you. Floor push = mass × (g + the lift's acceleration). Speed is not in the formula.

Try itA scale in a lift

A person stands on a bathroom scale in a lift. Change the lift's speed and its acceleration and watch the scale. Only one of them moves the needle.

Lift acceleration (up is +) 0 m/s²

Lift speed 0 m/s

Person 70 kg

Scale shows–

Floor pushes up–

You feel–

Lift is–

NumbersHow big is it?

The sim uses g = 9.81 m/s². Real lifts change acceleration smoothly, so the reading rises and falls gradually.

≈ 1 m/s²

How hard a typical passenger lift speeds up and slows down. A measured office lift in New York peaked at about 1.1 to 1.3 m/s².

77 / 70 / 63 kg

Scale reading for a 70 kg person at +1 m/s², cruising, and −1 m/s²: 70 × (9.81 ± 1) ÷ 9.81.

≈ 90%

Strength of Earth's gravity at the space station's height. Astronauts float because they are falling around the planet nonstop.

HowWhat happens, step by step

Gravity pulls you down with the same force the whole ride.
That pull is your real weight, and it doesn't change in a lift.
The floor has to push you along with the lift.
To speed you up upwards it pushes harder than your weight. To slow you down it pushes less.
You feel the floor's push, not your speed.
At any steady speed the floor pushes exactly your weight, so cruising feels like standing still.

Same in a plane: at 900 km/h the cabin feels like a living room, but take-off pushes you into your seat. Speed is just a number. Acceleration is what you feel.

Check3 quick questions

Bonus

Astronauts on the space station still feel about 90% of Earth's gravity pulling on them. They float because they're falling around the planet, nonstop. Cut the cable in the sim: the scale drops to zero.