A car goes from a town A to another town B with a speed of 40 km/h and returns back to the town A with a speed of 60 km/h. Calculate the average speed during the whole journey.

Solution

Let the total distance travelled to and fro be d
Speed while ging from town A to town B = 40 km/hr
Speed while coming back from town B to town A = 60 km/hr
Time taken to go to town B ,t₁ = $\frac{D i s \tan c e}{S p e e d}$

t₁= $\frac{\frac{d}{2}}{40} = \frac{d}{80}$

Time taken to return to town A, t₂ = $\frac{\frac{d}{2}}{60} = \frac{d}{120}$

Average speed = $\frac{Total distance}{toatl time}$

$= \frac{d}{\frac{d}{80} + \frac{d}{120}} = \frac{80 \times 120}{80 + 120} = \frac{9600}{200} = 48 k m / h r$

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Matter In Our Surroundings

A car goes from a town A to another town B with a speed of 40 km/h and returns back to the town A with a speed of 60 km/h. Calculate the average speed during the whole journey.

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Matter In Our Surroundings

A car goes from a town A to another town B with a speed of 40 km/h and returns back to the town A with a speed of 60 km/h. Calculate the average speed during the whole journey.

Some More Questions From Matter In Our Surroundings Chapter

Give reason for the following observations.We can get the smell of perfume sitting several metres away.

What is the physical state of water ata) 25°C b)00Cc)1000C

What is the physical state of water at0°C

What is the physical state of water at100°C

Give two reasons to justifyWater at room temperature is a liquid.

Give two reasons to justifyAn iron almirah is a solid at room temperature.

Why is ice at 273K more effective in cooling than water at the same temperature ?

What produces more severe burns, boiling water or steam ?

8. Name A, B, C, D, E and F in the following diagram showing state change :

Both boiling and evaporation convert a liquid into vapour. What is the difference between the two process

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

Give reason for the following observations.

We can get the smell of perfume sitting several metres away.

What is the physical state of water at

a) 25°C
b)0⁰C
c)100⁰C

What is the physical state of water at
0°C

What is the physical state of water at
100°C

Give two reasons to justify
Water at room temperature is a liquid.

Give two reasons to justify
An iron almirah is a solid at room temperature.