Question 338999
I've heard that tossing a coin into a fountain will bring me good luck, so I throw a silver dollar up with a velocity of 5m/sec. and it falls into the fountain 1.3 meters below my hand. How long is the coin in the air?
In this question i just really dont understand how to do quadratic equations when you dont have the acceleration unless its -9.8m/s squared, but really not sure.
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Yes, gravity is your acceleration.
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Applying the equation of motion:
h(t) = (1/2)gt + vt + vo
where
h(t) is height
g is gravity
v is initial velocity
t is time
vo is the initial height
.
h(t) = (1/2)(-9.8)t + 5t + 1.3
h(t) = -4.6t + 5t + 1.3
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set h(t) to zero and solve for t:
0 = -4.6t + 5t + 1.3
applying quadratic formula we get:
t = {-0.217, 1.304}
we can throw out the negative solution leaving:
t = 1.3 seconds
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Details of quadratic to follow:
*[invoke quadratic "x", -4.6, 5, 1.3 ]