Question

Solve this:

5. A particle at rest starts with acceleration 5 m/s² on a straight line for 4 s. The it decelerates at 2.5 m/s² to rest. Average velocity during the journey is.

(1) 20 m/s (2) 10 m/s

(3) 5 m/s (4) 15 m/s

Answer 1

Dear Student

$$\begin{gathered} abodyismovingfor4secwithacceleration5m{s}^{-2} \\ Inv-tgraph,slope=\frac{maximumvelocity}{timetaken} \\ 5=\frac{v_{max}}{4} \\ {v}_{max}=20m{s}^{-1} \\ Innexthalp \\ 2.5=\frac{20}{t\text{'}} \\ t\text{'}=8sec \\ Totaltime=8+4=12sec \\ totaldis\tan ce=1/2\times 12\times 20=120m \\ Averagevelocity=\frac{totaldis\tan ce}{totaltime}=120/12=10m{s}^{-1} \\ Regards \end{gathered}$$