Question #aa1f0

1 Answer
Oct 6, 2017

2114" km"2114 km

Explanation:

F = G.m.M/(r^2)F=G.m.Mr2

color(red)(g=10m/s^2g=10ms2

color(green)(M = 6times10^24kgM=6×1024kg (mass of the Earth)

color(blue)(G = 6.7times10^-11 Nm^2kg^-2G=6.7×1011Nm2kg2

color(orange)(m = 50kgm=50kg

color(violet)(r=6.4*10^6m = 6341kmr=6.4106m=6341km (Radius of earth)

Weight of m=mg=50kg times10m/s^2=color(indigo)(500Nm=mg=50kg×10ms2=500N

We need to find r' such that "Weight"= color(purple)(250N
(half the weight of a 50kg mass)

F = (G*m*M)/(r^2)

=>color(purple)(250N) = (color(blue)(6*10^-11)*color(green)(6*10^24)*color(orange)(50))/(r')^2= (1.8*10^16)/(r')^2

=>(r')^2=(1.8*10^16)/(250)=color(grey)(7.2*10^30

=>r'=sqrtcolor(grey)(7.2*10^30)~~8485281m~~color(blue)(8485km

So, distance from earth's surface =r'-r
=color(blue)(8485km-color(violet)(6341km))~~2114km