Question

a body is relased from a height equal to the radius R of earth . the velocity of the body with which it strikes the earth is

Answer 1

Answer:

A body is released from a height equal to radius of the earth R.

At the height above the surface of the earth.

mechanical energy, E

1

=K.E+P.E

E

1

=0−

R

GMm

=−

2R

GMm

. . . . .(1)

At the surface of the earth,

E

2

=

2

1

mv

2

−

R

GMm

. . . . .(2)

From the conservation of energy,

E

1

=E

2

−

2R

GMm

=

2

1

mv

2

−

R

GMm

2

1

mv

2

=

2R

GMm

v=

R

GM

=

R

2

GMR

. . . . . . .(3)

as we know that,

g=

R

2

GM

Equation (3) becomes

v=

gR

The correct option is A.

Explanation:

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