# How Does Tire Pressure Relate to Automobile Weight?

• imnotsmart
In summary, to measure pressure exerted on the floor when you stand on one foot, you would need to use an equation to calculate the required pressure, convert from meters to inches, and use that value to measure the pressure with a gauge.
imnotsmart
The four tires of an automobile are inflated to a gauge pressure of 2.2*10^5 Pa. Each tire has an area of 0.024 m2 in contact with the ground. Determine the weight of the automobile.

imnotsmart said:
The four tires of an automobile are inflated to a gauge pressure of 2.2*10^5 Pa. Each tire has an area of 0.024 m2 in contact with the ground. Determine the weight of the automobile.
SOLUTION HINTS:
{Weight of Auto} = {Number of Tires}*{Tire Gauge Pressure (ea tire in Pa = N/m^2)}*{Contact Area (each tire in m^2)}
Answer should be approx (21,120 N).

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A 81 kg man in a 4.0 kg chair tilts back so that all the weight is balanced on two legs of the chair. Assume that each leg makes contact with the floor over a circular area with a radius of 1.0 cm, and find the pressure exerted on the floor by each leg.

imnotsmart said:
A 81 kg man in a 4.0 kg chair tilts back so that all the weight is balanced on two legs of the chair. Assume that each leg makes contact with the floor over a circular area with a radius of 1.0 cm, and find the pressure exerted on the floor by each leg.
SOLUTION HINTS:
Use equation below to calculate required pressure. Remember to convert chair leg circle Radius from "cm" to "m".

$$\mbox{(Pressure Ea Chair Leg in N/m^2)} \ \ =$$

$$= \ \ \frac {\displaystyle \left \mathbf{\{} \mbox{(Mass of Man in kg)} + \mbox{(Mass of Chair in kg)} \right \mathbf{\}} \cdot \mbox{(9.81 m/sec^2)} } { \pi \cdot \mbox{(Ea Chair Leg Contact Circle \underline{Radius} \color{red}\textbf{in m}\color{black})}^{2} \cdot \mbox{(Number Chair Legs in Contact)} }$$

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so the radius squared is .0001 and the number chair legs in contact is two...correct?

imnotsmart said:
so the radius squared is .0001 and the number chair legs in contact is two...correct?
Correct.
(R^2 = 0.0001 m^2)
(# Chair Legs in Contact = 2)

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Ok, I figured that one out. This is the last one that I need help with if you don't mind.
Water is to be pumped to the top of a building which is 850 ft high. What gauge pressure is needed in the water line at the base of the building to raise the water to this height?

imnotsmart said:
Ok, I figured that one out. This is the last one that I need help with if you don't mind.
Water is to be pumped to the top of a building which is 850 ft high. What gauge pressure is needed in the water line at the base of the building to raise the water to this height?
SOLUTION HINTS:
Use equation below to compute pressure (in N/m^2). Remember to convert Height from "ft" to "m".
{Gauge Pressure (in N/m^2)} = {Water Density (in kg/m^3)}*(g)*{Height (in m)} =
= (1000 kg/m^3)*(9.81 m/sec^2)*{Height (in m)}

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thanks for all your help buddy

I have two more questions for anyone can help...
1. A frog in a hemispherical pod finds that he just floats without sinking in a fluid of density 1.25 g/cm3. If the pod has a radius of 9.00 cm and negligible mass, what is the mass of the frog?
2. A cowboy at a dude ranch fills a horse trough that is 1.6 m long, 60 cm wide, and 40 cm deep. He uses a 1.9 cm diameter hose from which water emerges at 1.4 m/s. How long does it take him to fill the trough?

how do you messure pressure that you exert on the floor when you stand on one foot ?

## 1. What is the difference between density and pressure?

Density is the measure of how much matter or mass is packed into a given volume, while pressure is the amount of force applied per unit area. In other words, density is the measure of compactness, while pressure is the measure of how that compactness affects the surroundings.

## 2. How are density and pressure related?

Density and pressure are directly related to each other. As the density of a substance increases, the pressure exerted by that substance also increases. This is because more densely packed molecules have a greater force of impact when colliding with a surface, resulting in a higher pressure.

## 3. How do you calculate density?

Density is calculated by dividing the mass of an object by its volume. The formula for density is density = mass/volume. The unit for density is often expressed in grams per cubic centimeter (g/cm3) or kilograms per cubic meter (kg/m3).

## 4. How do you convert between units of density and pressure?

To convert between units of density and pressure, you can use the relationship between the two: pressure = density x gravity x height. This means that if you know the density and height of a substance, you can calculate the pressure it is exerting. To convert between units, you can use conversion factors or online unit converters.

## 5. What are some real-life applications of density and pressure?

Density and pressure are important concepts in various scientific fields. In meteorology, density and pressure play a role in weather patterns and air pressure systems. In engineering, they are important in designing structures that can withstand high pressure. In chemistry, density and pressure are used in understanding the behavior of gases and liquids. Additionally, density and pressure are important in the study of oceanography, as well as in medical fields such as respiratory therapy and blood pressure monitoring.

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