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Ch. 17 - Temperature, Thermal Expansion, and the Ideal Gas Law
Giancoli Douglas - Physics for Scientists and Engineers 5th edition
Giancoli Douglas5th editionPhysics for Scientists and EngineersISBN: 9780137488179당신이 사용하는 게 아니라요?교과서 변경
17장, 문제 24a

Determine a formula for the change in surface area of a uniform solid sphere of radius r if its coefficient of linear expansion is α (assumed constant) and its temperature is changed by ∆T.

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1
Start by recalling the formula for the surface area of a sphere: \( A = 4\pi r^2 \), where \( r \) is the radius of the sphere.
The coefficient of linear expansion \( \alpha \) relates the change in length (or radius in this case) to the change in temperature \( \Delta T \) by the formula: \( \Delta r = \alpha r \Delta T \).
Substitute the new radius \( r + \Delta r \) into the surface area formula to find the new surface area: \( A' = 4\pi (r + \Delta r)^2 \).
Expand \( (r + \Delta r)^2 \) using the binomial theorem: \( A' = 4\pi (r^2 + 2r\Delta r + (\Delta r)^2) \).
Subtract the original surface area \( A = 4\pi r^2 \) from \( A' \) to find the change in surface area \( \Delta A \), and simplify using \( \Delta r = \alpha r \Delta T \). The final formula for \( \Delta A \) will be expressed in terms of \( \alpha \), \( r \), and \( \Delta T \).

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Coefficient of Linear Expansion

The coefficient of linear expansion (α) quantifies how much a material expands per unit length for each degree of temperature increase. It is a material-specific property that indicates how sensitive a material is to temperature changes. For solids, this expansion is typically uniform in all directions, which is crucial for understanding how dimensions change with temperature.
추천 영상:
가이드 코스
07:31
Linear Thermal Expansion

Surface Area of a Sphere

The surface area (A) of a sphere is calculated using the formula A = 4πr², where r is the radius. When the radius changes due to thermal expansion, the surface area will also change. Understanding how the radius varies with temperature is essential for determining the change in surface area as the sphere is heated or cooled.
추천 영상:
가이드 코스
09:18
Equipotential Surfaces

Thermal Expansion of Solids

Thermal expansion refers to the increase in size of a solid material when its temperature rises. For a uniform solid sphere, the change in radius (Δr) can be expressed as Δr = αrΔT, where ΔT is the change in temperature. This relationship allows us to derive how the surface area changes as the temperature varies, linking thermal expansion to geometric properties.
추천 영상:
가이드 코스
05:21
Volume Thermal Expansion
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