A 70 KG man is standing on a scale inside an elevator. Calculate the reading on a scale after the cable breaks and the elevator goes into free fall.
Free fall? Isn't the man falling at the same rate as the elevator, in a state of weightlessness?
will the scale read 0
yes.
Thank you
20
To calculate the reading on the scale after the cable breaks and the elevator goes into free fall, we need to consider the forces acting on the man.
When the elevator is at rest or moving at a constant speed, the scale measures the normal force exerted by the man's weight, which is equal to his mass multiplied by the acceleration due to gravity (9.8 m/s^2). So, when the elevator is not in free fall, the scale reading would be:
Scale reading = Mass × Acceleration due to gravity
Given that the man's mass is 70 kg, we can calculate the scale reading:
Scale reading = 70 kg × 9.8 m/s^2
Scale reading = 686 Newtons
Now, when the elevator goes into free fall, it means that it is accelerating downward at the same rate as gravity (9.8 m/s^2). In this scenario, the man will experience weightlessness as there is no normal force acting on him.
Therefore, when the cable breaks and the elevator is in free fall, the scale reading will be zero. The man will not exert any force on the scale since there is no normal force acting on him.
To summarize:
- When the elevator is not in free fall, the scale reading is 686 Newtons.
- When the elevator goes into free fall, the scale reading is zero.