Answer:
Explanation:
Conduction of heat through a thick layer is governed by the following relation
Q = KA( T₂ -T₁ ) / d
K is thermal conductivity of medium ( it is earth here ) , A is surface area though which heat conducts and T₂ -T₁ is temperature difference and d is thickness of medium through which heat conducts.
k = 8 units
A = surface area= 2πrL
= 2x 3.14 x 2/12 x 100
= 104.67 ft²
T₂ -T₁ = 70 - 42
= 28 F
d = thickness
= 30 /12 ft
= 2.5 ft
Putting the given values here
Q = ![\frac{8\times104.67\times28}{2.5}](https://tex.z-dn.net/?f=%5Cfrac%7B8%5Ctimes104.67%5Ctimes28%7D%7B2.5%7D)
= 9378.4 Btu per hour.
Answer:i think they do i dont understand your question it does not make sence
Explanation:
Answer: 47.28
Explanation:
just times 5.91 by 8 your welcome please leave a heart and five star
Answer:
Explanation:
Using the lens formula
1//f = 1/u+1/v
f is the focal length of the lens
u is the object distance
v is the image distance
For convex lens
The focal length of a convex lens is positive and the image distance can either be negative or positive.
Given f = 20cm and u = 10cm
1/v = 1/f - 1/u
1/v = 1/20-1/10
1/v = (1-2)/20
1/V = -1/20
v = -20/1
v = -20 cm
Since the image distance is negative, this shows that the nature of the image formed by the convex lens is a <u>virtual image</u>
<u></u>
For concave lens
The focal length of a concave lens is negative and the image distance is negative.
Given f = -20cm and u = 10cm
1/v = 1/f - 1/u
1/v = -1/20-1/10
1/v = (-1-2)/20
1/V = -3/20
v = -20/3
v = -6.67 cm
Since the image distance is negative, this shows that the nature of the image formed by the concave lens is a <u>virtual image</u>
<u></u>