Radius of a planet is three times the radius of the earth and it has s...
Radius of a planet is three times the radius of the earth and it has s...
Given:
Radius of the planet = 3 times the radius of the Earth
To find:
The ratio of escape speeds from the surface of the planet and the surface of the Earth
Formula:
The escape speed from the surface of a planet (v) can be given by the formula:
v = √(2GM/R)
where G is the gravitational constant, M is the mass of the planet, and R is the radius of the planet.
Analysis:
1. Radius of the planet:
Let's assume the radius of the Earth is R and the radius of the planet is 3R.
2. Mass of the planet:
The average density of the planet is the same as that of the Earth. Since density = mass/volume, the mass of the planet can be expressed as:
Mass of the planet = Average density of the planet × Volume of the planet
The volume of a sphere is given by the formula:
Volume of a sphere = (4/3)π(r^3)
where r is the radius of the sphere.
Since the radius of the planet is 3R, the volume of the planet can be expressed as:
Volume of the planet = (4/3)π((3R)^3) = (4/3)π(27R^3) = 36πR^3
Therefore, the mass of the planet can be expressed as:
Mass of the planet = Average density of the Earth × 36πR^3
3. Escape speed from the surface of the planet:
Using the formula for escape speed, we can express the escape speed from the surface of the planet as:
vplanet = √(2G × Mass of the planet / Radius of the planet)
4. Escape speed from the surface of the Earth:
Using the formula for escape speed, we can express the escape speed from the surface of the Earth as:
vearth = √(2G × Mass of the Earth / Radius of the Earth)
Calculation:
Substituting the values of mass and radius of the planet and the Earth into the formulas for escape speed, we get:
vplanet = √(2G × Average density of the Earth × 36πR^3 / 3R)
vearth = √(2G × Average density of the Earth × 4πR^3 / R)
Simplifying the equations, we get:
vplanet = √(24GπR^2)
vearth = √(8GπR^2)
Taking the ratio of vplanet to vearth, we get:
vplanet/vearth = √(24GπR^2) / √(8GπR^2)
vplanet/vearth = √(24/8)
vplanet/vearth = √3
Therefore, the ratio of the escape speeds from the surface of the planet to the surface of the Earth is 3:1, which corresponds to option D.
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