“if a cyclist travels at an average speed of 3m/s-1 and turns home at an average speed of 9m/s-1 than what is the average speed of the whole journey?”

using the equation speed= distance/time

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- September 17th 2007, 01:45 PMhana_102average speed.
“if a cyclist travels at an average speed of 3m/s-1 and turns home at an average speed of 9m/s-1 than what is the average speed of the whole journey?”

using the equation speed= distance/time - September 17th 2007, 03:23 PMSoroban
Hello, hana_102!

This is a classic Trick Question . . .

Quote:

If a cyclist travels at an average speed of 3m/s

and turns home at an average speed of 9m/s,

what is the average speed of the whole journey?

We will use: .

Suppose the distance (one way) is meters.

He cycled meters at 3 m/s.

. . This took him: . seconds.

He cycled back meters at 9 m/s.

. . This took him: . seconds.

The entire trip took: . seconds (Total time).

The total distance is: . meters.

Therefore, his average speed was: .

- September 18th 2007, 07:25 AMhana_102
Thanks for explaining, I understand how you got your answer, but what I don’t get is how you got 4/9 ?

Sorry if this seems silly. But how does d/3 + d/9= 4/9d?

Thank you - September 18th 2007, 08:28 AMSoroban
Hello, hana_102!

Don't kick yourself too hard . . .

. .

- September 18th 2007, 12:01 PMhana_102
Thank you. That seems so simple now that I look at it all worked out!!!!!!!! :eek: