# Projectile Motion Problem with no Velocity given

#### NatoMan

Problem is Linked with a graphic I drew. Thanks!

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#### Woody

S=S0+V0t+1/2At^2

Where S is the height above the ground
and A is the acceleration due to gravity
t is time.

Then it a simultaneous equation situation:
you know A (=g=9.82 m/s/s)
you know two values for S (at the start and at the wall)

From this you should be able to work out V0
(note that this is just the vertical component, use some trigonometry to get the horizontal component).

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#### Cervesa

$\Delta x = v_0\cos{\theta_0} \cdot t \implies t = \dfrac{\Delta x}{v_0\cos{\theta_0}}$

$\Delta y = v_0\sin{\theta_0} \cdot t - \dfrac{1}{2}gt^2$

eliminate the parameter, $t$

$\Delta y = \Delta x \tan{\theta_0} - \dfrac{g \cdot \Delta x^2}{2v_0^2 \cos^2{\theta_0}}$

evaluate where necessary & substitute the given values and solve for $v_0$

1 person