question_answer

A car travels equal distances in the same direction with velocities\[\text{6}0\text{ km }{{\text{h}}^{-\text{1}}},\text{ 2}0\text{ km}{{\text{h}}^{-\text{1}}}\]and\[\text{1}0\text{ km }{{\text{h}}^{-\text{1}}}\]respectively. Find the magnitude of average velocity of the car over the whole journey of motion

Answer:

We know, \[=\frac{total\,\,dis\tan ce\,\,travelled\,by\,\,the\,\,car}{total\,time\,\,taken}\] \[=\frac{S+S+S}{\frac{S}{60}+\frac{S}{20}+\frac{S}{10}}=\frac{S[3]}{S\left[ \frac{1}{60}+\frac{1}{20}+\frac{1}{10} \right]}\] \[=\frac{3}{\frac{1+3+6}{60}}=\frac{3\times 60}{10}=18km/hr\] \[=18\times \frac{5}{18}m/s\,s=5m{{s}^{-1}}\]