Question

A geo-stationary satellite is orbiting around the earth at height of $30,000km$ in circular orbit. The radius of the earth is taken as $6000km$. The geo-stationary satellite comes back to its position after one revolution in exactly $24$ hours. Let the acceleration due to gravity$\left(g\right)$ be $10m/s^2$ and mass of satellite be $1000kg$; calculate the work done in $12hours$ when moving under gravitational force.

• A. $3.6\pi \times {10}^{14}J$
• B. $2\pi \times 7.2\pi \times {10}^{14}J$
• C. $1.8\pi \times {10}^{14}J$
• D. $0J$

Answer 1

Answer: (D)

$0J$

Work done under centripetal force is always zero because force & displacement are perpendicular to each other.