Question

An artificial planet is moving in a circular orbit of radius $42250km$. Calculate its speed if it takes $24hours$ to revolve around the earth.

• A. $2.07km{s}^{-1}$
• B. $3.07km{s}^{-1}$
• C. $4.21km{s}^{-1}$
• D. $1.28km{s}^{-1}$

Answer 1

The correct option is B

$3.07km{s}^{-1}$

Speed $=\frac{\text{Circumference of trajectory}}{\text{Time period}}$$=\frac{2\pi R}{T}$$=\frac{2\times \pi \times 42250}{24\times 3600}km{s}^{-1}$ $[\because 1hr=60\times 60=3600s]$

$=3.07km{s}^{-1}$