Question

3. A lift is accelerated upward. Why will the apparent weight of a person inside the lift increase relative to its real weight? If the lift is going with uniform speed, then? justify your answer in both the cases.

Answer 1

$$\begin{gathered} \mathrm{Case}\mathrm{I}:(\mathrm{accelerated}\mathrm{upward}) \\ \mathrm{Apparent}\mathrm{weight},\mathrm{W}\text{'}=\mathrm{W}\left(1+\frac{\mathrm{a}}{\mathrm{g}}\right) \\ \mathrm{Here}\mathrm{a}\mathrm{is}\mathrm{positive},\mathrm{so}\mathrm{W}\text{'}>\mathrm{W} \\ \mathrm{Apparent}\mathrm{weight}\mathrm{increases}\mathrm{relative}\mathrm{to}\mathrm{real}\mathrm{weight}. \\ \mathrm{Case}\mathrm{II}:(\mathrm{Up}\mathrm{with}\mathrm{uniform}\mathrm{speed}) \\ \mathrm{Apparent}\mathrm{weight},\mathrm{W}\text{'}=\mathrm{W}\left(1+\frac{\mathrm{a}}{\mathrm{g}}\right) \\ \mathrm{Here},\mathrm{a}=0,\mathrm{so}\mathrm{W}\text{'}=\mathrm{W} \\ \mathrm{Apparent}\mathrm{weight}\mathrm{is}\mathrm{equal}\mathrm{to}\mathrm{real}\mathrm{weight} \end{gathered}$$