Question

The weight of a body of mass $3kg$ at a height of $12.8\times {10}^{6}m$ from the surface of the earth is _______.

• A. $9.75N$
• B. $1.46N$
• C. $3.26N$
• D. $4.36N$

Answer 1

The correct option is C $3.26N$

Given,

$Mass=3kg$

$,h=128\times {10}^8=12.8\times {10}^{7}m$

$R=6.4\times {10}^{6}m$

So, $h=12.8\times {10}^6=2R$

$g^{\prime }=g_m(\frac{R}{R+h}{)}^2=9.8(\frac{R}{R+2R}{)}^2=9.8(\frac{1}{3}{)}^2=\frac{9.8}{9}$

Thus the weight,

$W=m{g}^{\prime }=3\times \frac{9.8}{9}=3.26N$