Pressure of person on chair Question

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In summary, the person tries to solve a math problem involving pressure and force, but they don't understand it and need help. They calculate the area of the circle using the pi r squared formula, and find that 1.54-4=1.01 x 105 N/m2. They then try to use the force formula W=mg, but get a larger number than they should. They conclude that they need help understanding the problem.
  • #1
rijo664
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Homework Statement



A 67 kg person sits on a 3.6 kg chair. Each leg of the chair makes contact with the floor in a circle that is 1.4 cm in diameter.

Homework Equations


p= M/V
P= F/A
Pg = P - Pat
Pat = 1.01 x 105 N/m2

The Attempt at a Solution


I figured out the area of the circle using the pi r squared formula. This came out to be 1.54-4
But I can't figure out how to finish the problem. Just looking for any advice on what to do next. I thought I should figure out the force by using W=mg formula which I tried but my answer for pressure was larger. Which I felt wasn't right

Homework Statement


Homework Equations


The Attempt at a Solution

 
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  • #2
How many legs does the chair have?
 
  • #3
It doesn't say how many legs the chair has. So I believe we should assume that the chair has 4 legs
 
  • #4
rijo664 said:
It doesn't say how many legs the chair has. So I believe we should assume that the chair has 4 legs

Then if you did divide the force of gravity by 4 times the area of one leg, I wouldn't know what was wrong with it.
 
  • #5
Use the total area of the legs. The weight is distributed over the 4 legs.
 
  • #6
Here is the question again. I don't understand it?

A 67 {\rm kg} person sits on a 3.6 {\rm kg} chair. Each leg of the chair makes contact with the floor in a circle that is 1.4 {\rm cm} in diameter.

Here is what they want me to find - Find the pressure exerted on the floor by each leg of the chair, assuming the weight is evenly distributed.

Here are the equations that might be helpful to solve this problem

p= M/V (density formula)
P= F/A (pressure formula)
pg= P - Pat (gauge pressure formula)
at = 1.01 x 105 N/m2

This is what I did?

I found the Area by using pi r2

Here is what I need help with?

What should I do next. I thought I could find force by using the formula W=mg. But that didn't work my pressure answer was a big number
 
  • #7
It should work. Use W=mg to find the force, and P=F/A to find the pressure. You should get a big number, because the area of all the legs combined is a very small compared to a square meter. (and the pressure you get will be in Newtons per square meter)

If you still get a wrong answer give your complete calculation.
 
  • #8
Thank you. That really helped
 

Related to Pressure of person on chair Question

What is the pressure of a person on a chair?

The pressure of a person on a chair is the amount of force that the person's body exerts on the chair's surface. It is usually measured in units of pounds per square inch (psi) or newtons per square meter (N/m²).

What factors affect the pressure of a person on a chair?

The pressure of a person on a chair can be affected by several factors, including the weight of the person, the surface area of the chair that is in contact with the person's body, and the distribution of weight on the chair.

Does the type of chair affect the pressure of a person on it?

Yes, the type of chair can affect the pressure of a person on it. Chairs with larger surface areas and more cushioning tend to distribute the weight of a person more evenly, resulting in lower pressure. On the other hand, chairs with smaller surface areas and less cushioning may cause higher pressure on the person's body.

How does posture affect the pressure of a person on a chair?

The posture of a person can greatly affect the pressure on a chair. Sitting in an upright position with proper alignment of the spine can distribute weight more evenly and result in lower pressure. However, slouching or leaning to one side can increase pressure on certain areas of the body and cause discomfort.

What are the potential health risks of high pressure on a chair?

High pressure on a chair can lead to discomfort, pain, and potentially serious health issues such as pressure ulcers, also known as bedsores. Prolonged sitting on a chair with high pressure can also restrict blood flow and lead to poor circulation, which can increase the risk of developing blood clots.

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