Answer:
c. expanded polyurethane
Explanation:
Thermal performance of a building fabric is measured in terms of heat loss and is expressed as U-value or R-value. U-value is the rate of heat transferred through a structure divided by the difference in temperature across the structure with a unit of measurement of W/m²K.You can calculate the U-value of a by getting the reciprocal of the sum of thermal resistances , R, making the building material.
If you have the value of R, then U=1/R
Material size R U
plywood 1" 1.25 0.8
Poured concrete 2" 0.99 1.010
Expanded polyurethane 1" 6.5 0.1538
Asbestos shingles 1" 0.03 33.33
The material with lowest U-value is expanded polyurethane
Explanation:
Blue or violet light has the shortest wavelength. White light is a combination of all colors in the color spectrum.
In the given problem, we say various information's that are going to help us reach the ultimate answer to the question. Let us first write the information's that have been presented in front of us.
Mass of the car = 2000 kg
Velocity of the car = 25 m/s^2
Radius of the circle = 80 m
Now we already know the equation for calculating the centripetal force and that is
Centripetal Force = [mass * (velocity)^2]/Radius
= [2000 * (25)^2]/80
= (2000 * 625)/80
= 1250000/80
= 15625
So the centripetal force on the car is 15625 Newtons
Answer:
The magnitude of the gravitational force is 4.53 * 10 ^-7 N
Explanation:
Given that the magnitude of the gravitational force is F = GMm/r²
mass M = 850 kg
mass m = 2.0 kg
distance d = 1.0 m , r = 0.5 m
F = GMm/r²
Gravitational Constant G = 6.67 × 10^-11 Newtons kg-2 m2.
F = (6.67 × 10^-11 * 850 * 2)/0.5²
F = 0.00000045356 N
F = 4.53 * 10 ^-7 N
Answer:
The initial energy level = 6
Explanation:
Photon wavelength is proportional to energy. The wavelength of emitted photons is related to the energy levels of the atom as given by the Rydberg formula:
ₕ₁₂
(1/λ) = Rₕ [(1/n₂²) − (1/n₁²)]
where n₂ = final energy level = 2
n₁ = initial energy level = ?
Rₕ = Rydberg's constant = 1.097 × 10⁷ m⁻¹
λ = wavelength = 410 nm = 410 × 10⁻⁹ m
1/(410 × 10⁻⁹) = (1.097 × 10⁷) [(1/2²) − (1/n₁²)]
0.223 = [(1/4) − (1/n₁²)]
(1/n₁²) = 0.02778
n₁² = 1/0.02778 = 36
n₁ = 6.
