Question

A car travels at 54 km/h for first 20 s, 36 km/h for next 30 s and finally 18 km/h for next 10 s. Find its average speed.

Answer 1

39 km/h, or 10.8333 m/s

Step-by-step explanation:

The average speed is equal to total distance over total time

The formula for distance is s=v×t

So the average speed would be:

v=(v1×t1)+(v2×t2)+(v3×t3)/t1+t2+t3

Now we can solve:

v=(54×20)+(36×30)+(18×10)/60s

v=2340/60

v=39km/h

If you need to convert to m/s, divide by 3.6 and you get 10.8333 m/s

Hope this helps!