Answer:
Rayon
Wool
Silk Yarn
Explanation:
Rayon
This is Fabric A. Rayon basically burns very quickly even quicker than fabrics like cotton and linen. Its ash is gray in color. The rayon fabric smells of burning paper when it is burnt.
Wool:
This is Fabric B. Wool is basically hard to ignite. It burns slowly. Its ash is dark in color. The wool fabric smells of burning hair when it is burnt.
Silk Yarn:
This is Fabric C. The silk yarn shrinks from the flame when it is burned. It has a grayish black ash. The silk yarn fabric smells burnt meat of when it is burnt.
Mass m = 68 kg
center of gravity from his palms x = 0.7 m
center of gravity from his feet x ' = 1 m
forces exerted by the floor on his palms and feet are F and F ' respectively.
with respect to palms :---------------------
( F*0 ) - (W * x ) + [ F ' * (x+x') ] = 0
-mg*0.7 + F ' * 1.7 = 0 where W = weight = mg
F ' * 1.7 = mg * 0.7
F ' = mg * 0.7 / 1.7
= 68 *9.8 * ( 0.7 / 1.7 )
= 274.4 N
with respect to feet :--------------------
( F ' * 0 ) -( W* x ' ) + [F * ( x + x') ] = 0
-mg*1 + [ F * 1.7 ]= 0
F = mg / 1.7
= 392 N
r₁ = distance of the point from the source = 43 km = 43000 m
I₁ = intensity of earthquake wave at distance "r₁" = 2.5 x 10⁶ W/m²
r₂ = distance of the point from the source = 1.5 km = 1500 m
I₂ = intensity of earthquake wave at distance "r₂" = ?
we know that , for a constant power , the intensity of wave is inversely proportional to the distance from the source .
I α 1/r² where I = intensity of wave , r = distance from source
hence we can write
I₁/I₂ = r₂²/r₁²
inserting the values
(2.5 x 10⁶) /I₂ = (1500/43000)²
I₂ = 2.1 x 10⁹ W/m²