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**Physics Kinematics Unit: Question concering Projectile Motion**

## Homework Statement

If a high jumper reaches her maximum height as she travels across the bar,

**determine the initial velocity**she must have to clear a

*bar set at 2.0 m*if her

*range during the jump is 2.0 m*. What assumptions did you make to complete the calculations?

Range(d) = 2.0 m

Acceleration due to gravity (a) = 9.81 m/s^2 down

The height of the bar = 2.0 m

## Homework Equations

[tex] a= \frac{Vf - Vi}{t} [/tex]

[tex] d=(Vi)(t) + (1/2)(a)(t^2) [/tex]

[tex] d=Vt [/tex]

## The Attempt at a Solution

This is my attempt. Since Vix is O, we can determine time using this equation:

[tex] d=(Vi)(t) + (1/2)(a)(t^2) [/tex]

[tex] 2.0 m = (0)(t) + (1/2) (9.81 m/s^2) (t^2)[/tex]

[tex] t = 0.64 s[/tex]

Now trying to find Vix, use this equation:

[tex] d = vt[/tex]

[tex] 2.0 m = V(0.64) [/tex]

[tex] v = 3.13 \frac {m}{s} [/tex]

Now You have to divide the time by 2, because that's half way through the jump, her maximum height would be half the time.

[tex] t = \frac {0.64}{2} [/tex]

[tex] t = 0.32 s [/tex]

Now find Viy, using this equation:

[tex] d = Vt[/tex]

[tex] 2.0 = V(0.32)[/tex]

[tex] v = 6.2 \frac {m}{s}[/tex]

Now find Vi using this this equation:

[tex] a^2 + b^2 = c^2 [/tex]

[tex] 6.25^2 + 3.13 ^2 = c^2[/tex]

[tex]c= 6.99 m/s (63 degrees)[/tex]

I got this wrong, but I'm just showing you my attempt to this question

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