Question

distance between station A and B is 200km. A train starts from A at a velocity of 54km /hr and covers half of the distance. then it changes its velocity to 72km/hr and reaches B . find the avg velocity ​

Answer 1

Answer:

61.71 Km/hr

Explanation:

time taken to cover first 100 Km is

$\frac{100}{54}hrs$

time taken to cover next 100 Km is

$\frac{100}{72} hrs$

Average velocity is

$\frac{ \frac{100}{54} \times 54 + \frac{100}{72} \times 72}{ \frac{100}{54} + \frac{100}{72} }$

$= \frac{200 \times 54 \times 72}{100(54 + 72)} = \frac{2 \times 54 \times 72}{126}$

$= 61.71 \: \: km {hr}^{-1}$