Question

The mass of moon is 1% of mass of earth. The ratio of gravitational pull of earth on moon and that of moon on earth will be:

• A. 1 : 1
• B. 1 : 10
• C. 1 :100
• D. 2 : 1

Answer 1

The correct option is A 1 : 1

$The$ $gravitational$ $pull$ $on$ $earth$ $by$ $the$ $moon$ $is$ $the$ $same$ $as$ $that$ $of$ $the$ $pull$ $on$ $the$ $moon$ $by$ $the$ $earth.$ $It$ $is$ $because$ $while$ $calculating$ $the$ $force$ $we$ $make$ $use$ $of$ $masses$ $of$ $both$ $the$ $objects$ $as,$ $F_{12}$ $=$ $F_{21}$ $=$ $\frac{G{M}_{Earth}{M}_{Moon}}{r^2}$ $where$ $r$ $is$ $distance$ $between$ $them$. $Therefore$ $the$ $ratio$ $of$ $gravitational$ $pull$ $on$ $the$ $moon$ $by$ $earth$ $to$ $the$ $pull$ $on$ $earth$ $by$ $the$ $moon$ $will$ $be,$ $F_{12}$ $:$ $F_{21}$ $=$ $1:1$