Solving Elevator Problem Homework Statement

• Anthonyphy2013
In summary: The scale is for the woman only.scale reads 50kg?In summary, during the elevator's upward acceleration, the woman's scale will read approximately 50kg, as the apparent weight will be equal to her actual weight due to the elevator's acceleration canceling out the additional force from the hoisting cable.
Anthonyphy2013

Homework Statement

A woman stands on a scale in a moving elevator. Her mass is 50kg and the combined mass of the elevator accelerates upward. During the acceleration , the hoisting cable applies a force of 9350N. What does the scale read during the acceleration ?

Homework Equations

F net= T-MG= Ma
Apparent weight = mg(a/g+1)

The Attempt at a Solution

First we find a and the plug in the a in the apparent weight and we find the scale reading
first attempt: 9530-(50+815) = (815+50)a
and a= 1.22m/s^2
and the apparent weight = 9532N

Anthonyphy2013 said:

Homework Statement

A woman stands on a scale in a moving elevator. Her mass is 50kg and the combined mass of the elevator accelerates upward. During the acceleration , the hoisting cable applies a force of 9350N. What does the scale read during the acceleration ?

Homework Equations

F net= T-MG= Ma
Apparent weight = mg(a/g+1)

The Attempt at a Solution

First we find a and the plug in the a in the apparent weight and we find the scale reading
first attempt: 9530-(50+815) = (815+50)a

You are mixing up Newtons with kg in this equation.
Your problem doesn't state it but I gather the mass of the elevator is 815 kg.

Where does the number 815 come from?
Please work with units, it is easier to spot errors that way. For example, you cannot subtract 50kg from 9350N, that does not make sense.

and the apparent weight = 9532N
It would be impossible to stand on a scale in that case (that is the weight of a car), the result cannot be true.

815 comes from the combined mass of the elevator and the scale .
9530N-(865*9.8)N=(865)a
a=1.22 m/s2
Apparent weight=N=Mg(a/g+1)
=(865*9.8)(1.22/9.8 + 1)
9532.3N
Is that corrected ?

Last edited:
Anthonyphy2013 said:
815 comes from the combined mass of the elevator and the scale .
You mean 815 is the mass of the elevator, I think.
9530N-(865*9.8)N=(865)a
a=1.22 m/s2
That is finally correct.
Apparent weight=N=Mg(a/g+1)
=(865*9.8)(1.22/9.8 + 1)
9532.3N
Is that corrected ?

No. She's not going to weigh much more than at rest. And the scale reads in kg, not N.
So the answer is not much more than 50 kg.

Anthonyphy2013 said:
Apparent weight=N=Mg(a/g+1)
=(865*9.8)(1.22/9.8 + 1)
865? Isn't that going to give you the apparent weight of the elevator+passenger?

haruspex said:
865? Isn't that going to give you the apparent weight of the elevator+passenger?

so you mean the mass is 50 not 865( 815+50) ?

Anthonyphy2013 said:
so you mean the mass is 50 not 865( 815+50) ?

Yes. You're not measuring the weight of the elevator, right?

1. What is the "Elevator Problem"?

The "Elevator Problem" refers to a common homework question or problem given in physics or engineering classes that involves determining the time, velocity, and/or distance traveled by an elevator in a given scenario.

2. How do you solve the Elevator Problem?

To solve the Elevator Problem, you need to use the equations of motion and apply them to the given scenario. This may involve breaking down the problem into smaller parts, using kinematic equations, or considering different forces acting on the elevator.

3. What are some common mistakes when solving the Elevator Problem?

Some common mistakes when solving the Elevator Problem include not properly identifying and considering all forces acting on the elevator, using incorrect equations or variables, and not properly setting up and solving the problem step-by-step.

4. What are some tips for solving the Elevator Problem efficiently?

To solve the Elevator Problem efficiently, it is important to clearly define and understand the given scenario, carefully label all variables and equations, and systematically solve the problem step-by-step. It may also be helpful to double-check your calculations and answer for reasonableness.

5. How can understanding the Elevator Problem be useful in real-life situations?

Understanding how to solve the Elevator Problem can be useful in real-life situations where you need to calculate the velocity, time, or distance of an object in motion. This can be applied to elevators, but also to other scenarios such as cars, projectiles, and more.

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