Find Initial Velocity given angle, distance, height launched from.

  • #1
1. A nerf gun in a vacuum is fired from .98 meters at an angle of 15degrees, going 7.86m. Find the initial velocity of the gun, then find the horizontal and vertical components of the initial velocity.

Knowns
g=-9.8m/s2
yo
=.98m
xo=0m
y=o ( the final height of the dart is 0)
x=7.86m
θ=11 degrees



Homework Equations


x=xo+vot
y=yo+vot+.5gt2
vox=vocosθ
voy=vosinθ

The Attempt at a Solution


So first i simplified the x equation down to get time on one side to get
(x-xo)/(vocos11)=t
Then i plugged in the numbers to get
{7.86/(vocos11)}=t

Then i plugged in the parts for the y equation,
-.98=voyt+-4.9t2
Now what do i do? do take out a t and plug in the x equation?

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
1,341
3
Why not substitute in v_0* sin (theta) = v_0y. Then you have two equations and two unknowns and from that everything else is easy to find!
 

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