Question

A bus decreases its speed from 80 km/h^-1 to 60 km/h^-1 in 5 s. Find the acceleration of bus

Answer 1

Dear Student,

$$\begin{gathered} \mathrm{u}=80\mathrm{km}/\mathrm{h}=80\times \frac{5}{18}\mathrm{m}/\mathrm{s} \\ \mathrm{u}=\frac{200}{9}\mathrm{m}/\mathrm{s} \\ \mathrm{v}=60\mathrm{km}/\mathrm{h}=60\times \frac{5}{18}\mathrm{m}/\mathrm{s} \\ \mathrm{v}=\frac{50}{3}\mathrm{m}/\mathrm{s} \\ \mathrm{t}=5\mathrm{s} \\ \mathrm{v}=\mathrm{u}+\mathrm{at} \\ \frac{200}{9}=\frac{50}{3}+\mathrm{a}\times 5 \\ 5\mathrm{a}=\frac{200-150}{9} \\ \mathrm{a}=\frac{50}{5\times 9}=\frac{10}{9}\mathrm{m}/{\mathrm{s}}^2 \end{gathered}$$