﻿ A body projected vertically from the earth reaches a height equal to earth's radius before returning to the earth. The power exerted by the gravitational force is greatest from Physics Gravitation Class 11 Manipur Board

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A body projected vertically from the earth reaches a height equal to earth's radius before returning to the earth. The power exerted by the gravitational force is greatest

• at the instant just before the body hits the earth

• it remains constant all through

• at the instant just after the body is projected

• at the highest position of the body

A.

at the instant just before the body hits the earth

We know

P = F. v = Fv cos θ

so just before hitting θ is zero and both F and v are maximum

We know

P = F. v = Fv cos θ

so just before hitting θ is zero and both F and v are maximum

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The position co-ordinates of two particles of masses m1 and m2are (x1, y1, z1) and (x2, y2, z2) respectively. Find the coordinates of the centre of mass.

The position vectors of masses m1 and m2 are respectively,

Let the position coordinates of the centre of mass be (X, Y, Z).

Therefore the position vector of centre of mass is,

Since,

Comparing the coefficients of  , we get

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