# A Car Travels 100 Km at a Speed of 60 Km/H and Returns with a Speed of 40 Km/H. Calculate the Average Speed for the Whole Journey. - Science

Sum

A car travels 100 km at a speed of 60 km/h and returns with a speed of 40 km/h. Calculate the average speed for the whole journey.

#### Solution

In the first case, the car travels at a speed of 60 km/h for a distance of 100 km.
Thus,
"Time" = "Distance travelled"/"Speed"
So , t1 = 100/60 hr
= 5/3 hr
In the second case, the car travels at a speed of 40 km/h for a distance of 100 km.
Thus,
"Time" = "Distance travelled"/"Speed"
So , t2 = 100/40 hr
= 5/2 hr
Total time taken :
= t1 + t2
= 5/3 + 5/2 hr
= 25/6 hr
Total distance travelled = 200 km
We can calculate average speed as:
"Average Speed" = "Tatal Distance travelled"/"Time"
Average speed for the entire journey :
= "(200)(6)"/25
= 48 km/hr

Concept: Measuring the Rate of Motion - Speed with Direction
Is there an error in this question or solution?

#### APPEARS IN

Lakhmir Singh Science Class 9 Physics
Chapter 1 Motion
Hots Questions | Q 59 | Page 22