We feel the difference in weight when we take the elevator and go up and down the high building. When we stand in a stationary elevator, we apply a force equal to our weight on the floor of the elevator, the elevator also applies equal weight to us and the reaction force is equal to our weight. But if the elevator continues to rise to the top, then an acceleration is created at the top of the elevator as it travels upwards from a fixed position. As a result our acceleration relative to the lift is greater than g . For this increased acceleration we apply more force than our weight on the lift. As we begin to descend, an acceleration is created from the stationary position and our acceleration relative to the lift is less than g . With this low acceleration we apply less force than our weight on the lift. As a result we feel lighter.