Apparent weight is the force exerted on an object by a surface, which we feel as our weight when standing in a lift.

How Lifts Change Your Weight

Your actual weight is the pull of gravity on your body, calculated as mass times acceleration due to gravity (W = mg). When you stand on a weighing scale inside a lift, the scale measures the Normal Force. The normal force is the upward push from the floor that stops you from falling through it. If the lift is stationary or moving at a constant speed, the normal force equals your weight. However, when the lift accelerates, this force changes, making you feel heavier or lighter.

Scenarios of Motion

• Moving Upwards: When the lift accelerates upward, the floor pushes against you harder than gravity pulls you down. Your apparent weight (R) becomes R = m(g + a), where 'a' is the acceleration. You feel heavier.
• Moving Downwards: When the lift accelerates downward, the floor drops away slightly, so it pushes up on you with less force. Your apparent weight becomes R = m(g - a). You feel lighter.
• Free Fall: If the lift cable breaks and it falls freely, the acceleration 'a' equals 'g'. Your apparent weight becomes R = m(g - g) = 0. You experience weightlessness.

A Concrete Example

Imagine a person with a mass of 50 kg (weighing about 490 Newtons on Earth). If the lift accelerates upward at 2 m/s², the scale will read 50 × (9.8 + 2) = 590 Newtons. Even though the person's mass remains 50 kg, the weighing scale shows a value equivalent to 60.2 kg. This proves that apparent weight depends entirely on the acceleration of the lift's frame of reference.