Question

A train travels 20km at a uniform speed of 60km/h and the next 20 km in 80km/h . Calculate its average speed.

Answer 1

avg velo.=d1+d2/t1+t2

=d+d/d/v1+d/v2

=2v1×v2/v1+v2

=2×60×80/60+80

=2×60×80/140

=480/7m/s

Answer 2

❄❄❄ Your solution ❄❄❄

________________________________________

Given Informations : -

Speed ¹ = 60 km/h

speed ² = 80 km/h

Distance = 20 km each time

so To find average speed ???

Time Taken ¹ = Distance /speed

=> 20/60 = 1/3 hrs

Time taken ² = 20/80 = 1/4 hrs

$average \: speed \: = \frac{total \: distance \: }{total \: time \: taken}$

$average \: speed \: = \frac{total \: distance \: }{total \: time \: taken}$

$av. \: speed \: = \frac{20 \: + \: 20}{ \frac{1}{3} + \frac{1}{4} }$

$average \: speed \: = \frac{total \: distance \: }{total \: time \: taken}$

$av. \: speed \: = \frac{20 \: + \: 20}{ \frac{1}{3} + \frac{1}{4} }$

$av.speed \: = \frac{40}{ \frac{7}{12} } \: km {h}^{ - 1}$

$average \: speed \: = \frac{total \: distance \: }{total \: time \: taken}$

$av. \: speed \: = \frac{20 \: + \: 20}{ \frac{1}{3} + \frac{1}{4} }$

$av.speed \: = \frac{40}{ \frac{7}{12} } \: km {h}^{ - 1}$

$av.speed \: = \frac{480}{7} \: km \: {h}^{ - 1}$

♥♥♥ Thank You ♥♥♥