Have you noticed you actually feel a little heavier than usual when an elevator accelerates upward, and lighter than usual when the acceleration is down?
Vidunenahawula Website (National Institute of Fundamental Studies)
You have two forces when you are in an elevator, the force of gravity and the upward normal force from the elevator. The normal force(N) is equal to your apparent weight. According to Newton’s 2nd Law of motion (F=ma), N = mg+ma if the elevator has an upward acceleration. The support must supply excess over the gravity force in order to accelerate upward. The scale has to push upward with extra force on the person to accelerate the person’s mass upward. So, you actually feel a little heavier than usual when the elevator accelerates upward. N = mg-ma if the elevator has a downward acceleration. The scale has to push upward with less force on the person to support the person’s weight. Therefore, the normal force is smaller, so the reading on the scale is a number that is less than the true weight.
