initial velocity


by Kr.m.h.
Tags: 2d kinematics, baseball, initial velocity
Kr.m.h.
Kr.m.h. is offline
#1
Sep22-13, 08:44 PM
P: 1
1. The problem statement, all variables and given/known data

According to the Guinness Book of World Records, the longest home run ever measured was hit by Roy “Dizzy” Carlyle in a minor league game. The ball traveled 188 m (618 ft ) before landing on the ground outside the ballpark.
Assuming the ball's initial velocity was 52 ∘ above the horizontal and ignoring air resistance, what did the initial speed of the ball need to be to produce such a home run if the ball was hit at a point 0.9 m (3.0 ft ) above ground level? Assume that the ground was perfectly flat.

2. Relevant equations

ΔX=Vicos(θ)T
ΔY=Visin(θ)T+.5aT2
Vx=Vicos(θ)T
Vy=Visin(θ)+aT
3. The attempt at a solution
I know the final velocity in the Y direction will be zero and the final position in the Y direction will also be zero. If I could solve for how long the baseball is in the air I could use the second equation I listed and solve for the initial velocity since the accelration is equal to -9.8m/s2. I'm not completely sure of how to go about solving this problem and I feel like there's something I'm over looking. Any suggestions?
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Simon Bridge
Simon Bridge is offline
#2
Sep22-13, 09:25 PM
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You have to use more than one equation. Start by listing everything you know and see if you can combine two equations. Careful: does your equation list account for the projectile (ball) starting higher than were it ends up.

I, personally, solve these questions using v-t graphs.


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