Answer:
a) 
Explanation:
a) the cross-sectional area of the hose would be the square of radius times pi. And since the sectional radius is half of its diameter d. We can express the cross-sectional area A1 in term of diameter d1

Answer:
The Universe became transparent to the light left over from the Big Bang when it was roughly 380,000 years old
Explanation:
Answer:
Sound waves travel faster in a low-density gas
Explanation:
First of all, let's remind that sound waves are pressure waves: they consist of oscillations of the particles in a medium, which oscillate back and forth along the direction of motion of the wave (longitudinal wave).
The speed of sound in an ideal gas is given by the equation

where
is the adiabatic index of the gas
p is the gas pressure
is the gas density
From the equation, we see that the speed of sound is inversely proportional to the square root of the density: therefore, the lower the density, the faster the sound waves.
So, sound waves will travel faster in a low-density gas.
Answer:
v=53.3m/s
Explanation:
Ek=1/2mv²
7.81×10⁴=1/2×55.0v²
v= the square root of 7.81×10⁴/0.5×55.0
v=53.3m/s
Answer:
Hey
The thickness of a planet's atmosphere determines the tempature. the reason why is because gas traps or reflects light. Gass molecules generally reflect light which means that photons bounce of gass molecules. But the space between these molecules allows most of the light to travel through and hit the planet.