It will travel slowest through gases.
Answer:
When substances made of iron are exposed to oxygen and moisture (water), rusting takes place. Rusting removes a layer of material from the surface and makes the substance weak. Rusting is a chemical change.
Answer:

Explanation:
distance between ship A and B = 32 mile
Ship A velocity in south, dx/dt = -16 mph
Ship B is sailing toward east with speed, dy/st = 12 mph
time = 1 hour
rate of change of distance between them = ?
x be the distance travel after t time
X = 32 + x
Let distance between them be z
now, using Pythagoras theorem to calculate distance between ships after 1 hours
z² = x² + y²
z² = (32 + x)² + 12²
z² = (32 - 16)² + 12²
z = √400
z = 20 miles
now, calculation of rate of change of distnace
z² = (32 + x)² + y²
differentiating both side w.r.t. time





hence, the rate is the distance between them changing at the end of 1 hour is equal to 
Answer:
Tu mujhe banaye ga face dekh aapna mirror me
Answer:
4 times greater
Explanation:
<u>Step 1:</u> Calculate light-collecting area of a 20-meter telescope (A₁) by using area of a circle.
Area of circle = π*r² =
Where d is the diameter of the circle = 20-m


A₁ = 314.2 m²
<u>Step 2:</u> Calculate light-collecting area of a 10-meter Keck telescope (A₂)

Where d is the diameter of the circle = 10-m

A₂ = 78.55 m²
<u>Step 3</u>: divide A₁ by A₂

= 4
Therefor, the 20-meter telescope light-collecting area would be 4 times greater than that of the 10-meter Keck telescope.