Physics - NLM Question with Solution | TestHub

When the girl is bending her legs, the total force exerted by her legs in the action, normal force by grand is the reaction. considering FBD of girl

$$\begin{array}{rlr}& {\overrightarrow{\mathrm{F}}}_{\mathrm{N}}+{\overrightarrow{\mathrm{F}}}_{\mathrm{w}}=\mathrm{ma}& {\overrightarrow{\mathrm{F}}}_{\mathrm{N}}=-{\overrightarrow{\mathrm{F}}}_{\mathrm{M}}\end{array}$$

So force on floor is ${\overrightarrow{\mathrm{F}}}_{\mathrm{M}}$ Resultant force on girl is ${\overrightarrow{\mathrm{F}}}_{\mathrm{W}}-{\overrightarrow{\mathrm{F}}}_{\mathrm{M}}$ Note : If we say the change in force of girl is ${\overrightarrow{\mathrm{F}}}_{\mathrm{M}}$, then (A) and (B) would also be correct.]