Answer:
- The difference in length for steel is 2.46 x 10⁻⁴ m
- The difference in length for invar is 1.845 x 10⁻⁵ m
Explanation:
Given;
original length of steel, L₁ = 1.00 m
original length of invar, L₁ = 1.00 m
coefficients of volume expansion for steel,
= 3.6 × 10⁻⁵ /°C
coefficients of volume expansion for invar,
= 2.7 × 10⁻⁶ /°C
temperature rise in both meter stick, θ = 20.5°C
Difference in length, can be calculated as:
L₂ = L₁ (1 + αθ)
L₂ = L₁ + L₁αθ
L₂ - L₁ = L₁αθ
ΔL = L₁αθ
Where;
ΔL is difference in length
α is linear expansivity = 
Difference in length, for steel at 20.5°C:
ΔL = L₁αθ
Given;
L₁ = 1.00 m
θ = 20.5°C

ΔL = 1 x 1.2 x 10⁻⁵ x 20.5 = 2.46 x 10⁻⁴ m
Difference in length, for invar at 20.5°C:
ΔL = L₁αθ
Given;
L₁ = 1.00 m
θ = 20.5°C

ΔL = 1 x 0.9 x 10⁻⁶ x 20.5 = 1.845 x 10⁻⁵ m
Answer:
It's Helium.
Explanation:
The superficial layers of the star compress the core as an effect of its own gravity. Therefore, atoms will be closer to each other in the core, allowing them to be combined.
A nuclear reaction occurs when light elements combine into heavier elements (that is known as nucleosynthesis). Different ways in which that can happen exist, but the most common in the Sun, according to its mass, is the Proton-Proton chain reaction. In that fusion reaction two atoms of Hydrogen are combined to form Helium.
Remember that a Helium atom is composed of two Protons and two Neutrons.
The Proton-Proton chain works in the following way:
+
=
+
+ 
Two Protons combine each other (
) and one Deuterium (
) is gotten, and one Neutrino (
), and one Positron (
) are emitted from them.
+
=
+ 
A deuterium and Proton combine each other and a Helium three nucleus(
) is gotten, and a gamma ray (
) is emitted.
+
=
+
+ 
Two Helium three nucleus combine and a Helium atom (
) is gotten, and two Protons are emitted.
So, when hydrogen atoms fuse together helium is created.
Explanation:
asi que sobre todo lol siento soy mexican y agora no se como escribir en ingles
It's a combination of substances that does not have uniform composition and properties.