Pressure exerted in an elevator

  • Thread starter Thread starter KingTutATL
  • Start date Start date
  • Tags Tags
    Elevator Pressure
AI Thread Summary
To calculate the pressure exerted by a suitcase in an accelerating elevator, the total force on the suitcase must include both gravitational force and the force due to the elevator's acceleration. The normal force can be calculated using the formula F_normal = m(a + g), where m is the mass of the suitcase, a is the elevator's acceleration, and g is the acceleration due to gravity. The pressure is then found by dividing this normal force by the area of contact between the suitcase and the floor. The area of the suitcase is 0.50m by 0.15m. This approach ensures that the pressure calculated accounts for the additional force from the elevator's upward movement.
KingTutATL
Messages
11
Reaction score
0
A suitcase (mass m=16kg) is resting on the floor of an elevator. The part of the suitcase in contact with the floor measures 0.50m by 0.15m. The elevator is moving upward, the magnitude of its acceleration being 1.5m/s^2. What pressure (in excess of atmospheric pressure) is applied to the floor beneath the suitcase?

This problem isn't too hard. Elevator is going up so the pressure will be greater than normal produced by the suitcase. Take the area of the suitcase and continue from there?
 
Physics news on Phys.org
KingTutATL said:
A suitcase (mass m=16kg) is resting on the floor of an elevator. The part of the suitcase in contact with the floor measures 0.50m by 0.15m. The elevator is moving upward, the magnitude of its acceleration being 1.5m/s^2. What pressure (in excess of atmospheric pressure) is applied to the floor beneath the suitcase?

This problem isn't too hard. Elevator is going up so the pressure will be greater than normal produced by the suitcase. Take the area of the suitcase and continue from there?
What is the force exerted on the suitcase by the floor? What is the area over which this force acts? That should be all you need.

AM
 
When calculating the force do I just add 1.5m/s^2 to 9.8m/s^2 and then calculate the force per area from there?
 
KingTutATL said:
When calculating the force do I just add 1.5m/s^2 to 9.8m/s^2 and then calculate the force per area from there?
Conceptually, the acceleration and gravity are different. You would add the force of gravity (weight) which the floor applies with no acceleration, to the force which the elevetor applies to accelerate the suitcase:

F_{normal} = ma + mg

AM
 
Of course, that's just
F_{normal}= m(a+ g)
as KingTutAtl asked.
 
HallsofIvy said:
Of course, that's just
F_{normal}= m(a+ g)
as KingTutAtl asked.
Of course. I should have begun my answer with: "Yes, provided you multiply by the mass". It appeared to me that the op was uncertain as to why you would add them together, since there is no acceleration due to gravity.

AM
 
Last edited:
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top