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
Answer:
Hello your question is incomplete hence I will give you a general answer on how A van de Graaff generator works
answer :
If the electrons falls through a PD of 150mV the electron will gain energy of 150MeV
Explanation:
when a Van de Graff generator is used to accelerate an electron through a PD ( potential difference ) of any value the particle ( electron ) the electron will gain energy ( eV ) which is is equivalent in value of the PD it accelerated through
hence if the electrons falls through a PD of 150mV the electron will gain energy of 150MeV
Answer:
Explanation:
From the question we are told that
Weight 
Altitude 
Speed 
Generally the equation for Potential energy ids mathematically given as
Answer:
due to the magnetic field
Explanation:
magnetic field is the same in the vacuum
Answer:
86605.08 N
Explanation:
The equation to calculate the force is:
Force = mass * acceleration
The force and the acceleration does not have the same direction in this case, so we need to decompose the force into its horizontal component, which is the force that will generate the horizontal acceleration:
Force_x = Force * cos(30)
Then, we have that:
Force_x = mass * acceleration
Force * cos(30) = 25000 * 3
Force * 0.866 = 75000
Force = 75000 / 0.866 = 86605.08 N
