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:
Circular motion: find period, find radius, find velocity, find centripetal acceleration 27 V= T a =vºlr=rw
Explanation:
Average velocity =
(displacement) / (time for the displacement)
and
(direction of the displacement) .
Displacement =
(distance from the start-point to the end-point)
and
(direction from the start-point to the end-point) .
When Ben is 200 meters from the corner store,
he is (500 - 200) = 300 meters from his house.
His displacement is
300 meters in the direction
from his house to the neighbor .
His average velocity is
(300/910) = 0.33 meters per second, in the
direction from his house to the neighbor .
Gravity is a non contact force , jump from a little high place (don't do that :P) , you wont just get stuck in the air you will fall down , this is gravity you dont need any contact
