Question

(11)A train moves : distance of 10m with a
constant speed of 40m/s & moves the next Sm
with a constant speed of 30m/s. Calculate its
ave pee speed.​

Answer 1

Distance covered by the train, s = 10 m

Speed of the train, $\sf v_1$ = 40 m/s

Speed of the train, $\sf v_2$ = 30 m/s

Average speed = $\sf v_{av}$

Time taken by the train, $\sf t_1$ = $\dfrac{s}{v}$

• $\sf t_1$ = $\dfrac{10}{40}$

• $\sf t_1$ = $\dfrac{1}{4}$ s

Time taken by the train, $\sf t_2$ = $\dfrac{s}{v}$

• $\sf t_2$ = $\dfrac{10}{30}$

• $\sf t_2$ = $\dfrac{1}{3}$ s

Total time, t = $\sf t_1$ + $\sf t_2$

• t = $\dfrac{1}{4}$ + $\dfrac{1}{3}$

• t = $\dfrac{3+4}{12}$ = $\dfrac{7}{12}$ s

Now, average speed, $\sf v_{av}$ = $\dfrac{T.D}{T.T}$

• $\sf v_{av}$ = $\dfrac{20×12}{7}$

• $\sf v_{av}$ = $\dfrac{240}{7}$ = 34.28 m/s

Hence, the average speed of the train is 34.28 m/s

$\bold{Hope\;it \; helps\;!}$