Question

a particle weight 270 on the surface of earth . at what height above the earths surface will its weight be 30 ?
Radius of the earth = 6400.

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Answer 1

Answer:

Here we have weight of particle at the surface of earth is 120N , i.e Ws=120N .

At the surface of earth F=GMm/R^2 , where M is the mass of earth ,m is the mass of particle and R is the radius of earth.

But we know that W=F=mg.

So, 120N=GMm/R^2 …….equation(1).

Let at the height of H the weight of particle is 30N.

Similarly ,

30N=GMm/(R+H)^2………equation(2).

By equation (1)÷equation(2).

We get,. 4 = (R+H/R)^2. (because mass doesn't change)

So, we get H= 64,00km.