Answer: 0 degrees Celsius or 32 degrees Fahrehit
Explanation:
Regardless of what direction an object is moving, the acceleration
due to gravity is always directed toward the center of the Earth.
That's the direction commonly known as "down".
Answer:
"It will be more than the speed of sound waves in air at 20*C and water at 20*C."
Explanation:
Speed of sound in a medium depends upon the density and elasticity of the medium.
If the elasticity of a medium is greater and the density of that medium is lower, sound will travel faster. Although density is also a factor but the major factor is Elasticity.
Hence, sound travel faster in solids than in liquids and even slower in gases due to elasticity difference.

That is why the speed of sound in glass will be more than the speed of sound waves in air at 20*C and water at 20*C.
Answer:
U = 11.67 W/m² °C
Explanation:
Inner diameter, d = 2.5 cm = 0.025 m
Thickness of the wall, t = 2 mm = 0.002 m
thus, the outer diameter, D = d + 2t = 0.025 + 2 x 0.002 = 0.029 m


Now, based on outside convection heat transfer
we have

on rearranging, we get

where,
are the perimeter respective to inner and and outer diameter
on substituting the values, we get

or
U = 11.67 W/m² °C