Concepts Of Physics MCQ Edition [Volume 1]PhysicsNewton's Laws of Motion
The force exerted by an elevator's floor on the foot of a person standing inside is greater than the person's weight if the elevator is
Options
- Atravelling downward and speeding up
- Btravelling upward and speeding up
- Ctravelling downward and slowing down
- Dtravelling upward and slowing down
Correct answer
C. travelling downward and slowing down
Step-by-step solution
Let N be the normal force exerted by the elevator floor and mg be the true weight of the person. Taking the upward direction as positive, the equation of motion for the person is N - mg = ma , where a is the acceleration of the elevator. This gives N = m(g + a) . For the normal force to be greater than the weight ( N > mg ), the acceleration a must be positive, meaning the net acceleration is directed upwards. An upward acceleration occurs in two scenarios: The elevator is travelling upward (positive velocity) and