Question

A cosmonaut is circling the earth in a satellite at $ 7 \,km/s $ at a height of $ 630\, km $ above the surface of earth. Calculate the centripetal force acting on the cosmonaut if his mass is $ 80 \,kg $ (take $ R_E = 6.37 \times 10^6\,m $ )

• A. zero
• B. 560 N
• C. 600 N
• D. 650 N

Answer 1

Answer: (B)

The orbital velocity of cosmonaut
$v_0 = 7\, km/s = 7000 \,m/s$
Radius $r = R_E + h$
$= (6.37 \times 10^6 + 0.63 \times 10^6)$
$= 7 \times 10^6\, m$
Centripetal force
$F = \frac{mv^2}{r}$
$=\frac{80\times (7000)^2}{7\times 10^6}$
$ = 560\,N$