Question

6) A car travels a certain distance with a speed of 50 km/h and returns with a speed of 40 km/h. calculate the average speed for the whole journey.

Answer 1

Given :

• A car travels a certain distance with a speed of 50 km/h.

• And returns with a speed of 40 km/h.

To find :

• The average speed for the whole journey =?

Step-by-step explanation :

Let, the distance traveled in the forward direction be x

Now,

Total distance, d (distance) = x + x = 2x

Time taken during forward journey, t₁ = x/50 h

Time taken during the return journey, t₂ = x/40 h

1st Case :

Total time taken, t = t₁ + t₂

Substituting the values, we get,

= x/50 + x/40

= 9x/200

Therefore, Total time taken = 9x/200

2nd Case :

As We know that,

Average Speed = Total distance/Total time taken

Substituting the values in the above formula, we get,

= 2x/9x/200

= 2x × 200/9x

= 400/9

= 44.44 km/h

Therefore, the average speed of the whole journey is 44.44 km/h.