- #1

- 4

- 0

- Thread starter tawnyman
- Start date

- #1

- 4

- 0

- #2

cepheid

Staff Emeritus

Science Advisor

Gold Member

- 5,192

- 38

Hi, welcome to PF!

Sign conventions are arbitrary. It's

That having been said, if you

- #3

Doc Al

Mentor

- 44,987

- 1,259

Not sure what you mean by 'final' velocity, but something in freefall can be moving up or down depending upon the exact problem. (Or not moving at all, for an instant.)

- #4

- 4

- 0

A cliff diver from the top of a 100 [m] cliff. He begins his dive by jumping up

with a velocity of 5 [m/s]. What is his velocity right before he hits the water?

if down is defined as negative and the equation used is vf^2=vi^2+2ad then the answer should be 44.6m/s but the answer on the site was -44.6m/s.

- #5

Doc Al

Mentor

- 44,987

- 1,259

He's moving down so his velocity should be negative. The site's answer is correct.if down is defined as negativeand the equation used is vf^2=vi^2+2ad then the answer should be 44.6m/s but the answer on the site was -44.6m/s.

- #6

- 4

- 0

- #7

Doc Al

Mentor

- 44,987

- 1,259

The calculator only gives you the positive square root of a number. You have to supply the negative sign based on your understanding of how he's moving. (Don't forget that a negative number squared is positive.)

- #8

- 4

- 0

that's totally the answer to my first question.=D thanks!You have to supply the negative sign based on your understanding of how he's moving. (Don't forget that a negative number squared is positive.)

- Replies
- 5

- Views
- 1K

- Last Post

- Replies
- 12

- Views
- 531

- Last Post

- Replies
- 4

- Views
- 2K

- Replies
- 2

- Views
- 557

- Replies
- 3

- Views
- 2K

- Replies
- 1

- Views
- 534

- Replies
- 1

- Views
- 2K

- Replies
- 2

- Views
- 17K

- Replies
- 19

- Views
- 1K

- Last Post

- Replies
- 9

- Views
- 2K