When the elevator is stopped, the two forces are equal and opposite, and the net force is zero. But if you accelerate upward, the net force must also be upward. This means that the normal force exceeds the force of gravity (shown by the lengths of the two arrows above). So you feel heavier as the normal force increases. We can call the normal force “apparent weight”.
You see? You’re in this box and it looks like nothing is changing, but you feel like you’re being pulled down by a stronger gravity. That’s because your Frames of Referencethe seemingly stationary elevator cabin is actually hurtling upwards. Basically, we go from how You see it in the system as someone apart from the system sees it.
Could you build an elevator on the moon and accelerate it brisk enough to regain its Earthly weight? In theory, yes. That’s Einstein’s equivalence principle: There is no difference between a gravitational field and an accelerating frame of reference.
Roundabout solution
But you see the problem: to maintain upward acceleration for several minutes, the elevator shaft would have to be absurdly high, and you would soon reach equally absurd speeds. But wait! There’s another way to get acceleration: travel in a circle.
Here’s a physics puzzle for you: What are the three controls in a car that accelerate? Answer: the gas pedal (to accelerate), the brake (to ponderous down), and the steering wheel (to change direction). Yes, all of these are acceleration!
Remember that acceleration is the rate of change of velocity, and here’s the most vital thing: Velocity in physics is a vector. It has a quantity we call velocity, but it also has a direction. Turn the car and you accelerate, even if your velocity doesn’t change.
What if you just drove in circles? Then you would be accelerating the entire time, not moving anywhere. This is called centripetal acceleration (ANDC), which means indicating the center: An object moving in a circle accelerates towards the center, and the magnitude of this acceleration depends on the speed (In) and radius (R):
Courtesy of Rhett Allain