Question

A car moving with velocity of 10m/sec can be stopped by application of a constant force F in a distance of 20m.If the velocity of the car is 30m/s it can be stoped by this force how many meters?

Answer 1

Dear Student,

$$\begin{gathered} {\mathrm{v}}^2-{\mathrm{u}}^2=2\mathrm{as} \\ \mathrm{If}\mathrm{u}=0,\mathrm{then} \\ {\mathrm{v}}^2=2\mathrm{as} \\ {\mathrm{v}}^2\mathrm{\alpha }\mathrm{s} \\ \mathrm{Therefore},\frac{{\mathrm{s}}_1}{{\mathrm{s}}_2}={\left(\frac{{\mathrm{v}}_1}{{\mathrm{v}}_2}\right)}^2 \\ {\mathrm{s}}_1=20\mathrm{m} \\ {\mathrm{v}}_1=10\mathrm{m}/\mathrm{s} \\ {\mathrm{v}}_2=30\mathrm{m}/\mathrm{s} \\ \Rightarrow \frac{20}{{\mathrm{s}}_2}={\left(\frac{10}{30}\right)}^2 \\ \Rightarrow {\mathrm{s}}_2=20\times \frac{900}{100} \\ \Rightarrow {\mathrm{s}}_2=180\mathrm{m} \end{gathered}$$