Question

A train moves 20km at a uniform speed of60km/hr and next 20km at the uniform speed of80km/hr.calculate it’s average speed

Answer 1

Hiii..
Here is your answer..

Solution:-
Distance first(D1)=20km
Speed first(S1)=60km/h
So,
Time(T1)=Distance/speed
$= > \frac{20}{60} = \frac{1}{3}$
Now,
Distance second(D2)=20km
Speed second(S2)=80km/h
So,
Time (T2)=
$= > \frac{20}{80} = \frac{1}{4}$
Now,
Total distance=20+20=40km
Total time=
$= > \frac{1}{3} + \frac{1}{4} \\ = > \frac{4 + 3}{12} = \frac{7}{12}$
$average \: speed = \frac{total \: distance}{total \: time}$
$= > \frac{40}{ \frac{7}{12} } \\ = > \frac{40 \times 12}{7}$
$= > \frac{480}{7} \\ = > 68.57$
Hence,the average speed=68.57km/h

Hope it helps uh... ✌️✌️✌️