Why you feel heavier in an elevator (but your mass never changes)
In short: When an elevator lurches upward, you feel a sudden heaviness in your feet. Does this mean your body has gained weight? The answer lies in the distinction between the matter you are made of and the physical force of a floor pushing back against you.
To understand why elevators trick your senses, you must distinguish between three different physical concepts: mass, gravitational force, and weight. Your mass—the actual amount of matter in your body—is constant regardless of your motion. Similarly, the Earth's gravitational pull remains essentially the same whether you are on the ground floor or the top floor of a building. The sensation of 'weight' is actually the third concept: the upward push from the surface beneath you, known as the normal force.
When an elevator accelerates upward, the floor must push against your feet with more force than gravity alone to move you. This increased pressure is what a scale measures, causing the numbers to jump. Conversely, when an elevator slows down at the end of a downward trip, it decelerates, and the floor's upward push eases, making you feel lighter. You are essentially feeling the floor's reaction to your motion, not a change in your physical makeup.
This principle explains why astronauts on the International Space Station feel weightless. At an altitude of about 250 miles (400 kilometers), Earth's gravity is still about 90% as strong as it is on the surface. Yet, since the facility remains in perpetual free fall—traveling horizontally at over 17,000 mph (27,300 km/h)—the surface fails to support those inside. Without that upward push, gravity is still present, but weight is perceived as zero.
Ultimately, you cannot 'feel' gravity; you only feel the resistance of the ground preventing you from falling. Elevators provide a brief, controlled manipulation of that resistance, creating a temporary illusion of changing weight through the mechanics of relative motion.
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Sources
- Summary by Intellect · source: Would you weigh less in an elevator? - Carol Hedden
- Also: Would you weigh less in an elevator? - Carol Hedden | TED-Ed
- Also: Do you weigh more when an elevator goes up or when it comes down? | Live Science
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