FISIKA KELAS XI | SUHU DAN KALOR (PART 4) - PEMUAIAN

Summary

In this video, Yusuf Mada explains the concept of thermal expansion in physics, covering length, area, and volume expansion. He introduces the relevant formulas for calculating expansion and walks through practical examples, including the linear expansion of a metal rod and the volumetric expansion of mercury in a glass tube. The video highlights how temperature changes affect materials differently and provides clear steps for solving related problems, offering viewers valuable insights into the science of thermal expansion.

Takeaways

• 😀 Thermal expansion occurs when materials expand upon heating, increasing in size in three forms: length, area, and volume.
• 😀 The formula for **linear expansion** is: Δl = l₀ × α × ΔT, where α is the coefficient of linear expansion, and ΔT is the temperature change.
• 😀 **Area expansion** follows the formula: ΔA = A₀ × β × ΔT, where β = 2α, and A₀ is the initial area.
• 😀 **Volume expansion** is calculated using: ΔV = V₀ × γ × ΔT, with γ = 3α, and V₀ being the initial volume.
• 😀 The relationship between the coefficients of expansion: β (area expansion) is twice the coefficient of linear expansion (α), and γ (volume expansion) is three times α.
• 😀 An example shows how to calculate the length increase of a metal rod when heated, with a known α value and temperature change, resulting in a 1.1 mm expansion.
• 😀 In another example, a glass tube filled with mercury expands due to heating, causing mercury to spill out. This involves calculating the increase in volume of mercury and the glass.
• 😀 The spilled mercury volume is calculated by subtracting the volume change of the glass from the mercury’s volume change.
• 😀 Using the formula for volume expansion, the example shows how to calculate a 1.53 cm³ spill of mercury from a heated glass tube.
• 😀 The key to solving expansion problems is understanding the coefficients of expansion for different materials and applying the correct formulas based on the type of expansion (linear, area, or volume).

Q & A

What is the concept of expansion (pemuaian) in physics?

Expansion refers to the increase in size or volume of a material when it is heated. This can happen in three ways: linear expansion (change in length), area expansion (change in surface area), and volume expansion (change in volume).

How do we calculate the change in length (Delta l) for linear expansion?

The formula for calculating the change in length is: Delta l = l0 * Alpha * Delta T, where l0 is the initial length, Alpha is the coefficient of linear expansion, and Delta T is the change in temperature.

What is the relationship between the coefficients of linear expansion (Alpha), area expansion (Beta), and volume expansion (Gamma)?

The coefficient of area expansion (Beta) is twice the coefficient of linear expansion (Alpha), and the coefficient of volume expansion (Gamma) is three times the coefficient of linear expansion (Alpha).

What does the formula Delta A = A0 * Beta * Delta T represent?

This formula calculates the change in area (Delta A) during thermal expansion, where A0 is the initial area, Beta is the coefficient of area expansion, and Delta T is the change in temperature.

How do we calculate the change in volume (Delta V) for volume expansion?

The formula for calculating the change in volume is: Delta V = V0 * Gamma * Delta T, where V0 is the initial volume, Gamma is the coefficient of volume expansion, and Delta T is the change in temperature.

In the example with the piece of iron, how is the change in length calculated?

The change in length (Delta l) is calculated by substituting the given values into the formula: Delta l = 1 * 11 * 10^-6 * 100, which results in a change in length of 1.1 mm.

What happens when a glass tube filled with mercury is heated?

When the glass tube and mercury are heated, the volume of the mercury expands more than the volume of the glass, causing mercury to overflow or spill out of the tube.

How do we calculate the volume of mercury that will spill out of the tube?

To calculate the volume of mercury that will spill, we use the formula: V_spill = V0 * (Gamma_mercury - Gamma_glass) * Delta T, where V0 is the initial volume, Gamma_mercury and Gamma_glass are the coefficients of volume expansion for mercury and glass, respectively, and Delta T is the change in temperature.

What is the reasoning behind mercury overflowing when the glass tube is heated?

The mercury overflows because its volume expands more than the glass tube’s volume when both are heated, causing the excess mercury to spill out of the tube.

In the given example, what is the volume of mercury that overflows?

The volume of mercury that overflows is calculated as 0.153 cm³, based on the coefficients of volume expansion for both mercury and glass and the change in temperature.