A planet has mass 1/10 of that of earth, while radius is 1/3 that of earth. If a person can throw a stone on earth surface to a height of 90m, then he will be able to throw the stone on that planet to a height.
Correct Answer :
100m
Solution :
The correct option is 100m.
To find the height to which a person can throw a stone on the planet, we need to compare the acceleration due to gravity on the planet with that on Earth.
Step 1: Formula for acceleration due to gravity
The acceleration due to gravity () on the surface of a celestial body of mass and radius is given by the formula:
where is the universal gravitational constant.
Let the mass of Earth be and its radius be . The acceleration due to gravity on Earth is:
Step 2: Calculate gravity on the planet
For the planet, we are given:
Mass of the planet,
Radius of the planet,
Substituting these values into the formula for gravity on the planet ():
Simplifying the expression:
Step 3: Relationship between height and gravity
When a stone is thrown vertically upward with an initial velocity , the maximum height it attains is given by the kinematic equation:
Assuming the person throws the stone with the same initial velocity on both Earth and the planet, the height is inversely proportional to gravity:
Therefore, we can write the ratio of heights as:
Step 4: Calculate the height on the planet
Substitute the values of and into the ratio:
Solving for :
Thus, the person will be able to throw the stone to a height of 100m on that planet.
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