Physics
Physics
Problem
a. Show that the apparent weight of a body of mass placed on a weighing machine inside a lift descending with uniform acceleration is . b. What will be the reading of the weighing machine when the lift cable snaps and the lift falls freely? Express your answer in terms of .Intuitive explanation
The key to apparent weight is recognizing that a scale reads the normal force pushing up on you, not your true weight. When the lift accelerates downward, the net force on your body must point downward (toward the center of acceleration), so the upward normal force becomes smaller than —you feel lighter. In free fall, there's no normal force at all because gravity alone provides all the acceleration needed, so the scale reads zero.
Intuitive explanation
The key to apparent weight is recognizing that a scale reads the normal force pushing up on you, not your true weight. When the lift accelerates downward, the net force on your body must point downward (toward the center of acceleration), so the upward normal force becomes smaller than —you feel lighter. In free fall, there's no normal force at all because gravity alone provides all the acceleration needed, so the scale reads zero.