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Ch.10 - Gases
Chapter 10, Problem 15c

A person weighing 75 kg is standing on a threelegged stool. The stool momentarily tilts so that the entire weight is on one foot. If the contact area of each foot is 5.0 cm2, calculate the pressure exerted on the underlying surface in (c) pounds per square inch

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Convert the weight of the person from kilograms to pounds using the conversion factor: 1 kg = 2.20462 lbs.
Calculate the force exerted by the person in pounds. Since weight is a force, use the converted weight in pounds.
Convert the contact area from square centimeters to square inches using the conversion factor: 1 cm^2 = 0.1550 in^2.
Calculate the pressure exerted on the surface using the formula: Pressure = Force / Area.
Express the pressure in pounds per square inch (psi) using the values obtained from the previous steps.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Pressure

Pressure is defined as the force applied per unit area. In this context, it is calculated by dividing the weight of the person by the contact area of the stool's foot that is in contact with the ground. The formula for pressure (P) is P = F/A, where F is the force (weight) and A is the area.
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Unit Conversion

Unit conversion is the process of converting a quantity expressed in one set of units to another. In this problem, the pressure needs to be expressed in pounds per square inch (psi). This requires converting the area from square centimeters to square inches and ensuring that the weight is in pounds, which may involve converting kilograms to pounds.
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Force due to Gravity

The force due to gravity acting on an object is calculated using the equation F = mg, where m is the mass of the object and g is the acceleration due to gravity (approximately 9.81 m/s² on Earth). For this problem, the person's weight in pounds can be determined by converting their mass from kilograms to pounds, which is essential for calculating the pressure exerted on the surface.
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Related Practice
Textbook Question

(c) Which is most likely to be a gas at room temperature and ordinary atmospheric pressure, F2, Br2, K2O?

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Textbook Question

A person weighing 75 kg is standing on a threelegged stool. The stool momentarily tilts so that the entire weight is on one foot. If the contact area of each foot is 5.0 cm2, calculate the pressure exerted on the underlying surface in (a) bars

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Textbook Question

A person weighing 75 kg is standing on a threelegged stool. The stool momentarily tilts so that the entire weight is on one foot. If the contact area of each foot is 5.0 cm2, calculate the pressure exerted on the underlying surface in (b) atmospheres

Textbook Question

A set of bookshelves rests on a hard floor surface on four legs, each having a cross-sectional dimension of 3.0 x 4.1 in contact with the floor. The total mass of the shelves plus the books stacked on them is 266 kg.

Calculate the pressure in pascals exerted by the shelf footings on the surface.

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Textbook Question

(a) How high in meters must a column of ethanol be to exert a pressure equal to that of a 100-mm column of mercury? The density of ethanol is 0.79 g/mL, whereas that of mercury is 13.6 g/mL. Assume that the density of the water is 1.00 5 1.00 3 103 kg/m3. The gravitational constant is 9.81 m/s2, and 1 Pa 5 1 kg/ms2.

Textbook Question

(b) What pressure, in atmospheres, is exerted on the body of a diver if she is 10 m below the surface of the water when the atmospheric pressure is 100 kPa? Assume that the density of the water is 1.00 5 1.00 3 103 kg/m3. The gravitational constant is 9.81 m/s2, and 1 Pa 5 1 kg/ms2