Question

What is the average speed of a car in a journey in which it moves with a speed of 40km/h for 1h and then at 55km/h for 2h?

Answer 1

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✦ Required Answer:

♦️ GiveN:

• Speed for 1st hour = 40 km/hr
• Speed for next two hours = 55 km/hr

♦️ To FinD:

• Average speed of the body.....?

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✦ How to Solve ?

The concept behind the question is Average speed which is total distance by total time travelled. Whenever You get such question, always try to find the total distance and time by whatever data you have, Then by using the simplest Average speed formula, You can easily solve.

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✦ Solution:

We know that,

$\large{ \boxed{ \rm{ \purple{Speed = \frac{Distance}{Time}}}}}$

So, from here we can say that,

• Distance = Speed × time

We have speed = 40 km/hr and 1 hr, then distance

By using formula,

$\large{ \rm{ \longrightarrow \: Distance = 40 \: km {h}^{ - 1} \times1 \: hr}} \\ \\ \large{ \rm{ \longrightarrow \: Distance = 40 \: km}}$

Now, the other part of the journey,

We have speed = 55 km/hr and time = 2 hours

By using formula,

$\large{ \rm{ \longrightarrow \: Distance = 55 \: km {h}^{ - 1} \times 2 \: hr}} \\ \\ \large{ \rm{ \longrightarrow \: Distance = 110 \: km}}$

Now, as we have got

• Total distance = 40 + 110 = 150 km
• Total time = 1 + 2 = 3 hrs

Using the formula for Average speed,

$\large{ \boxed{ \rm{ \purple{Avg. \: speed = \frac{Total \: distance}{Total \: time}}}}}$

Here, we can get our answer,

$\large{ \rm{ \longrightarrow \: Avg. \:speed = \frac{150 \: km}{3 \: hr}}} \\ \\ \large{ \rm{ \longrightarrow \: Avg. \: speed = \boxed{ \rm{ \red{50 \: km {h}^{ - 1}}}}}} \\ \\ \large{ \therefore{ \underline{ \green{ \rm{Hence, \: solved \: \dag}}}}}$

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