Question

The value of g on the earth's surface is $980 \mathrm {~cm} / \mathrm { sec } ^ { 2 }$ . Its value at a height of 64 km from the earth's surface is

(Radius of the earth R = 6400 kilometers)

• A. $960.40 \mathrm {~cm} / \mathrm { sec } ^ { 2 }$
• B. $984.90 \mathrm {~cm} / \mathrm { sec } ^ { 2 }$
• C. $982.45 \mathrm {~cm} / \mathrm { sec } ^ { 2 }$
• D. $977.55 \mathrm {~cm} / \mathrm { sec } ^ { 2 }$

Answer 1

Answer: (A)

$960.40 \mathrm {~cm} / \mathrm { sec } ^ { 2 }$

Answer 2

$\frac { g ^ { \prime } } { g } = \left( \frac { R } { R + h } \right) ^ { 2 } = \left( \frac { 6400 } { 6400 + 64 } \right) ^ { 2 }$ $\Rightarrow$ $g ^ { \prime } = 960.40 \mathrm {~cm} / \mathrm { s } ^ { 2 }$