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

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SUMMARY

The discussion focuses on calculating the pressure exerted on the floor by each leg of a chair when a 72 kg person sits on it. The total weight, including the chair's mass of 4.0 kg, is 76 kg, leading to a force (F) of 745.56 N when multiplied by the gravitational constant (g = 9.81 m/s²). The area (A) of contact for each leg, calculated using the formula A = πr² with a diameter of 1.1 cm, results in an area of 9.5 x 10^-5 m². The pressure (P) is then determined by dividing the total force by the area, but the calculation must account for the four legs of the chair, which was initially overlooked.

PREREQUISITES
  • Understanding of basic physics concepts, specifically force and pressure.
  • Familiarity with the formula P = F/A for calculating pressure.
  • Knowledge of area calculation using A = πr².
  • Ability to convert units from centimeters to meters accurately.
NEXT STEPS
  • Review the concept of pressure distribution in systems with multiple supports.
  • Learn about unit conversions, particularly between centimeters and meters.
  • Explore the implications of weight distribution on pressure calculations.
  • Practice similar problems involving pressure calculations in physics.
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in understanding pressure calculations in real-world scenarios, particularly in contexts involving weight distribution and support systems.

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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.

Homework Equations



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.
 
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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.

Homework Equations



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.
 

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