• # question_answer 14) The engine of a motorcycle can produce a maximum acceleration$5\text{ }m/{{s}^{2}}$. Its brakes can produce a maximum retardation$10\text{ }m/{{s}^{2}}$. What is the minimum time in which it can cover a distance of 1.5 km? A) 30 secB)              15 secC) 10 sec              D) 5 sec

If a body starts from rest with acceleration a and then retards with retardation P and comes to rest. The total time taken for this journey is t and distance covered is S then $S=\frac{1}{2}\frac{\alpha \beta {{t}^{2}}}{(\alpha +\beta )}\,\,=\,\,\frac{1}{2}\frac{5\times 10}{(5+10)}\,\times \,\,{{t}^{2}}$ $\Rightarrow \,\,1500\,\,=\,\,\frac{1}{2}\frac{5\times 10}{(5+10)}\,\times \,\,{{t}^{2}}$ $t\,\,=\,\,30\,sec$