Question

13. A bus travels 1st 150 km is one
dimensional motion with 25 kmph, next
200 km with 50 kmph. What must its
speed in last 150 km such that the net
average speed for 500 km is 20 kmph
(1)10 kmph
(2)15 kmph
(3) 20 kmph
(4) 25 kmph​

Answer 1

Answer:

20 kmph is the correct answer

Answer 2

Given:-

• A bus travels 1st 150 km is one  dimensional motion with 25 kmph, next  200 km with 50 kmph.

To find:-

• Its  speed in last 150 km such that the net  average speed for 500 km is 20 kmph.

Solution:-

We know :

❥ Vavg = Total distance travelled / Total time taken

❥ t = distance / time

Therefore ,

➫ t1 = 150 / 25

➫ t2 = 200/50

➫ t3 = 150/v

We should now find " v " .

Given that , V avg = 20kmph.

According to question :

➫ 20 =500 /(150/25)+(200/50)+(150/v)

⇒ 20 = 500 / 6+4 +(150/v)

⇒ 500 = 20 ( 10+150/v )

⇒ 30 = 2×150 / v

⇒ V = 10 kmph .

∴ Speed in last 150 km such that the net  average speed for 500 km is 20 kmph is 10 kmph.

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