- #1
shawli
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Homework Statement
A child throws a snowball with a horizontal velocity of 18m/s directly toward a tree, from a distance of 9.0m and a height above the ground of 1.5m.
a) After what time interval does the snowball hit the tree?
b) At what height above the ground does the snowball hit the tree?
Homework Equations
displacement on x = horizontal velocity * time
displacement on y = initial vertical velocity * time + 0.5 * acceleration * time squared
or
displacement on y = final vertical velocity * time - 0.5 * acceleration * time squared
The Attempt at a Solution
For a), using the first formula, the calculation is:
9.0 m = 18m/s * t
t= 0.5s
Now I'm not sure what to do with b). If I use the equation:
displacement on y = initial vertical velocity * time + 0.5 * acceleration * time squared
is the initial vertical velocity 0? Since the boy throws the snowball horizontally? I think it is, but I don't get the right answer when I do this (the answer is 0.3 m).
What I'm doing is:
displacement on y = (0) * (0.5) + 0.5 * (-9.8) * (0.5)^2