The characteristics of thermal expansion allow finding that the response for a material without thermal expansion is
- The length variation is zero
- In the graph the line is horizontal so there is no change in length with temperature
Thermal expansion is the macroscopic sum of the changes in the length of the bonds when the energy (temperature) changes, it can be written
ΔL = α L₀ ΔT
Where ΔL is the change in length, α the coefficient of linear expansion, L₀ the initial length and ΔT the change in body temperature
In this case, a material is being designed that the thermal expansion is very small, for this the material must be made up of several compounds where some of them present a contraction with temperature, some examples: water at low temperature, liquefied gases , ceramic tile, quartz, etc.
The thermal expansion measurement processes control the body temperature and measure the change in length, in this case the change in length must be zero, in the attachment we can see a graph of a composite material with these characteristics, an example of this type of material is Invar an alloy of nickel and iron α = 3.7 10⁻⁶ ºC⁻¹
In conclusion, using the characteristics of thermal expansion we can find that the response of material without thermal expansion is
- The length variation is zero
- In the graph the line is horizontal so there is no change in length with temperature
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Answer:
Explanation:
a ) Let angle of incidence and angle of refraction be i and r respectively .
submarine is 300 m away from the shore . The point where laser strikes the surface of sea is 90 m horizontally away .
Tan r = 90 / 120
= 3 / 4
.75
r = 37 degree
c ) sini / sin37 = 1.333
sini = .8
i = 53 degree
Tan 53 = 210 / h , h is height of the building .
h = 210 / tan 53
= 158 m
Answer:
Explanation:
mass of balloon (m) = 12.5 g = 0.0125 kg
density of helium = 0.181 kg/m^{3}
radius of the baloon (r) = 0.498 m
density of air = 1.29 kg/m^{3}
acceleration due to gravity (g) = 1.29 m/s^{2}
find the tension in the line
the tension in the line is the sum of all forces acting on the line
Tension =buoyant force + force by helium + force of weight of rubber
force = mass x acceleration
from density = \frac{mass}{volume} , mass = density x volume
- buoyant force = density x volume x acceleration
where density is the density of air for the buoyant force
buoyant force = 1.29 x (\frac{4]{3} x π x 0.498^{3}) x 9.8 = 6.54 N
- force by helium = density x volume x acceleration
force by helium = 0.181 x (\frac{4]{3} x π x 0.498^{3}) x 9.8 = 0.917 N
- force of its weight = mass of rubber x acceleration
force of its weight = 0.0125 x 9.8 = 0.1225 N
- Tension = buoyant force + force by helium + force of weight of rubber
the force of weight of rubber and of helium act downwards, so they
carry a negative sign.
- Tension = 6.54 - 0.917 - 0.1225 = 5.5 N
Broad internalism, conventionalism, pluralistic internalism