Determine your ave. speed and ave. velocity

[Tonia]

Homework Statement

You swim from one end of the pool to the other end along a straight path with a speed of 6m/sec and you swim back to the starting point along the same path with a speed of 5m/sec. The length of the pool is unknown. Determine you ave. speed for the round trip. How much is your ave. velocity?

Homework Equations

Ave. velocity = Vf + Vo/2

The Attempt at a Solution

I know how to find the ave. velocity, but not the ave. speed.
Ave. velocity = Vf + Vo/2 = 5m/sec + 6m/sec/2 = 11m/sec/2 = 5.5 m/sec ave. velocity

 

[RyanH42]

Velocity is the vector.quantity.So I think you need to calculate net displacement vector then dividing total time.This will give you ave. velocity
For ave. speed you need to think total traveled distance divided by total time.

http://hyperphysics.phy-astr.gsu.edu/hbase/vel2.html It may help you

 

[Tonia]

But how do I know the distance traveled or the time? It doesn't show these in the problem so how do I find the ave. speed and ave. velocity without those numbers?

 

[RyanH42]

You don't need any numbers to find ave. velocity.But for ave speed use your formula.

 

[billy_joule]

But how do I know the distance traveled or the time? It doesn't show these in the problem so how do I find the ave. speed and ave. velocity without those numbers?

You have enough information.
The 5.5m/s you've calculated is the average speed, not velocity.
When you return to your starting point, what is your net displacement?

 

[RyanH42]

You have enough information.
The 5.5m/s you've calculated is the average speed, not velocity.
When you return to your starting point, what is your net displacement?

I am trying to tell this from the begining

 

[Tonia]

Ave Speed = distance traveled/time elapsed = ? I don't know the distance or the time.

 

[Tonia]

The net displacement is 0?

 

[RyanH42]

The net displacement is 0?

True

 

[RyanH42]

Ave speed=Total Distnace/Total Time.Lets suppose length of pool is x so total distance will be 2x.Now time is t=x/v so total time is x/5+x/6.Find the ave speed now

 

[Tonia]

and the ave. velocity is the net displacement divided by the time which would be 0 divided by 0 equals 0 ave. velocity?

 

[RyanH42]

and the ave. velocity is the net displacement divided by the time which would be 0 divided by 0 equals 0 ave. velocity?

Yes,correct

 

[billy_joule]

and the ave. velocity is the net displacement divided by the time which would be 0 divided by 0 equals 0 ave. velocity?

Time is not zero. It takes time to swim to the end and back. But, yes, displacement is zero so ave. velocity is zero (v = 0/t = 0)

 

[RyanH42]

Time is not zero

I didnt see that ,sorry