# Pressure of Chair Legs: Find F/A for 72 kg Person

• eagles12
In summary, the problem involves finding the pressure exerted by each leg of a chair that has a 72 kg person sitting on it. Using the equation P=F/A and the area of a circle equation A=∏r^2, the attempt at a solution involved finding the combined mass of the person and chair, calculating the force using gravity, and converting the diameter of the leg contact area into meters. However, the solution did not take into account the four legs of the chair and did not include units of measurement.
eagles12

## Homework Statement

A 72 kg person sits on a 4.0 kg chair. Each leg of the chair makes contact with the floor in a circle that is 1.1 cm in diameter. Find the pressure exerted on the floor by each leg of the chair, assuming the weight is equally distributed.

P=F/A
A=∏r^2

## The Attempt at a Solution

To find the force, I added the mass of the person and the mass of the chair and got m=76kg. Then i multiplied that by g=9.81 and got F=745.56.
To find the area, I converted 1.1 cm into meters, .011, and found the area A=9.5*10^-5
then i divided F/A and got P=7845260 but this is incorrect.

eagles12 said:

## Homework Statement

A 72 kg person sits on a 4.0 kg chair. Each leg of the chair makes contact with the floor in a circle that is 1.1 cm in diameter. Find the pressure exerted on the floor by each leg of the chair, assuming the weight is equally distributed.

P=F/A
A=∏r^2

## The Attempt at a Solution

To find the force, I added the mass of the person and the mass of the chair and got m=76kg. Then i multiplied that by g=9.81 and got F=745.56.
Okay, that's good.

To find the area, I converted 1.1 cm into meters, .011, and found the area A=9.5*10^-5
then i divided F/A and got P=7845260 but this is incorrect.
Did you recall that the chair has four legs? Oh, and be sure to include units of measurement.

## 1. What is the formula for calculating pressure?

The formula for calculating pressure is pressure equals force divided by area (P = F/A). This means that the amount of pressure exerted on an object is dependent on the amount of force applied and the area over which it is spread.

## 2. How does the weight of a person affect the pressure exerted by chair legs?

The weight of a person does not directly affect the pressure exerted by chair legs. Instead, it is the force of the person's weight divided by the area of the chair legs that determines the pressure. Therefore, a heavier person sitting on the same chair will exert more pressure than a lighter person.

## 3. Why is it important to consider the pressure of chair legs?

The pressure of chair legs is important to consider because it can impact the stability and durability of the chair. If the pressure is too high, it can cause the chair to break or damage the floor it is resting on. Additionally, high pressure can also cause discomfort for the person sitting on the chair.

## 4. How can the pressure of chair legs be reduced?

The pressure of chair legs can be reduced by increasing the surface area over which the force of the person's weight is spread. This can be achieved by using chairs with wider or more stable legs, adding cushions, or using floor protectors to distribute the weight over a larger area.

## 5. Is there an ideal pressure for chair legs?

There is no specific ideal pressure for chair legs as it depends on various factors such as the weight of the person, the design of the chair, and the type of flooring. However, it is generally recommended to distribute the weight evenly and keep the pressure at a level that is comfortable and safe for both the person and the chair.

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