# Projectile motion of long jump

1. Oct 13, 2009

### zman2011

1. The problem statement, all variables and given/known data
During a high school track meet, an athlete performing the long jump runs and leaps at an angle of 25 degrees and lands in a sand pit 8.8 m from his launching point. If the launch point and landing point are at the same height, y=0m, with what apeed does the athlete land?

2. Relevant equations

3. The attempt at a solution
Im completely stumped. any help would be appreciated.

2. Oct 13, 2009

### mvantuyl

Are you familiar with the range formula?

3. Oct 13, 2009

### zman2011

no i am not.

4. Oct 13, 2009

### zman2011

can anyone tell me what the range formula is?

5. Oct 13, 2009

### mvantuyl

R = ((v0)2 sin(2$$\theta$$0)) / g

Rearranging this formula and solving for v0 will give you the initial velocity. You can figure out the final velocity from there.

6. Oct 13, 2009

### zman2011

well then how do i find initial velocity to put it in.

7. Oct 13, 2009

### zman2011

i didnt see the second part of that. sorry. thank you

8. Oct 13, 2009

### zman2011

im having trouble with this. i keep getting initial velocity as a decimal

9. Oct 13, 2009

### Jebus_Chris

Maybe you aren't substituting/manipulating properly.

$$x = \frac{v_o^2sin2\theta}{g}$$
$$v_o=\sqrt{\frac{xg}{sin2\theta}}$$

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