Question

Q.A scooterist moves from a place A to place B with uniform speed of 30 km/h and returns from B to A with uniform speed of 50 km/h.Find the average speed for the complete journey..​

Answer 1

ANSWER:

• The average speed for the complete journey = 37.5 m/s.

GIVEN:

• A scooterist moves from a place A to place B with uniform speed of 30 km/h.

• Again moves from B to A with uniform speed of 50 km/h.

TO FIND:

• The average speed for the complete journey.

EXPLANATION:

$\boxed{\bold{\large{\gray{Avg \ speed=\dfrac{Total\ distance}{Total\ time}}}}}$

Let the distance from A to B and B to C be S.

Total distance = S + S = 2S

$\boxed{\bold{\large{\gray{Time=\dfrac{Distance}{Speed}}}}}$

$\sf \leadsto Total \ time = T_1 + T_2$

$\sf \leadsto T _1 =\dfrac{S}{30}$

$\sf \leadsto T _2=\dfrac{S}{50}$

$\sf \leadsto T_1 + T_2 = \dfrac{S}{30} + \dfrac{S}{50}$

$\sf \leadsto Total \ time = \dfrac{S}{30} + \dfrac{S}{50}$

$\sf \leadsto Avg\ speed=\dfrac{2S}{\dfrac{S}{30} + \dfrac{S}{50}}$

$\sf \leadsto Avg\ speed=\dfrac{2S}{S \left \lgroup\dfrac{1}{30} + \dfrac{1}{50} \right \rgroup}$

$\sf \leadsto Avg\ speed=\dfrac{2}{ \left \lgroup\dfrac{1}{30} + \dfrac{1}{50} \right \rgroup}$

$\sf \leadsto Avg\ speed=\dfrac{2}{\dfrac{5 + 3}{150} }$

$\sf \leadsto Avg\ speed=\dfrac{2}{\dfrac{8}{150} }$

$\sf \leadsto Avg\ speed=\dfrac{2 \times 150}{8}$

$\sf \leadsto Avg\ speed=\dfrac{150}{4}$

$\sf \leadsto Avg\ speed=\dfrac{75}{2}$

$\sf \leadsto Avg\ speed=37.5 \ m {s}^{ - 1}$

Hence the average speed for the complete journey = 37.5 m/s.

Answer 2

Answer:

Simply, see in attachment..

Thanks for following me..

20thanks = InBox..