- #1

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To find average speed, you add up the speeds / total speeds there are? (Eg. (10+20)/2)

Am I correct?

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- Thread starter cmkc109
- Start date

- #1

- 103

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To find average speed, you add up the speeds / total speeds there are? (Eg. (10+20)/2)

Am I correct?

- #2

jtbell

Mentor

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To find average velocity, you do total displacement over total time

Correct.

To find average speed, you add up the speeds / total speeds there are? (Eg. (10+20)/2)

No, you take the total distance along the path traveled, over the total time. For "total distance", imagine tracing out the path with a string, then straightening the string and measuring its length with a ruler.

- #3

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thanks for your reply! but when do you use v1 + v2 /2 ? or did i remember this wrong?

- #4

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thanks for your reply! but when do you use v1 + v2 /2 ? or did i remember this wrong?

You can use (v1+v2)/2 for the average speed if you first moved with speed v1 and then with speed v2 for the same amount of time. (

For constant acceleration in a straight line, the average speed (and velocity as well) is [itex] \frac {v_i + v_f}{2} [/itex]. the average of initial and final speed.

- #5

NascentOxygen

Staff Emeritus

Science Advisor

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Hi. I think you forgot some parentheses.thanks for your reply! but when do you use v1 + v2 /2 ? or did i remember this wrong?

You use that formula when acceleration is constant and you need to find the velocity at a time midway between the time that you measure velocity as v1 and the time you measure velocity as v2.

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