Question

Gud evening all
Hey guys..
Answer this one

Question :) The distance between Delhi and Agra is 200 km. A train travels the first 100 km at a speed of 50km/h. How fast must the train travel the next 100 km, so as to average speed of 70 km/h for the whole journey.

This question is from
Science - Physics
Motion

Do not spam please.
Correct answer are only allowed here.. ​

Answer 1

Answer:

The required speed is 116.67 km/h

Explanation:

Given :

• The distance between Delhi and Agra is 200 km.
• A train travels the first 100 km at a speed of 50 km/h

To find :

the speed of the train for the next 100 km so the average speed is 70 km/h for the whole journey.

Solution :

Speed = distance covered/time taken

⇒ time taken = distance covered/speed

Let's first find the time taken by the train to travel the first 100 km.

distance covered = 100 km

speed = 50 km/h

➣ time taken = 100/50

➣ time taken = 2 hours

Let 'v km/h' be the required speed to travel the next 100 km.

distance covered = 100 km

speed = v km/h

➣ time taken = 100/v hours

We know,

Average speed = total distance covered/total time taken

$\sf 70 = \dfrac{100+100}{2+\dfrac{100}{v}} \\\\ \sf 70= \dfrac{200}{2+\dfrac{100}{v}} \\\\ \sf 2+\dfrac{100}{v}=\dfrac{200}{70} \\\\ \sf 2+\dfrac{100}{v}=\dfrac{20}{7} \\\\ \sf \dfrac{100}{v}=\dfrac{20}{7}-2 \\\\ \sf \dfrac{100}{v}=\dfrac{20-14}{7} \\\\ \sf \dfrac{100}{v}=\dfrac{6}{7} \\\\ \sf v=\dfrac{7}{6} \times 100 \\\\ \sf v=\dfrac{700}{6} \\\\ \longrightarrow \sf v=116.67 \ km/h$

Therefore, the train must travel the next 100 km at a speed of 116.67 km/h so as to average speed of 70 km/h for the whole journey.

Answer 2

Answer:

hi,

I am Akshara,

from India,

9th class,

❣❣❣❣