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Awesomesauce
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Homework Statement
Sandy is throwing a stone at a plum tree. The stone is thrown from a point O at a speed of 35 ms^-1 at an angle [tex]\alpha[/tex] to the horizontal, where cos [tex]\alpha[/tex] = 0.96. You are given that, t seconds after being thrown, the stone is (9.8t - 4.9t^2)m higher than O.
When descending, the stone hits a plum which is 3.675m higher than O. Air resistance should be neglected.
Calculate the horizontal distance of the plum from O.
Homework Equations
Quadratic formula.
s = u t?
The Attempt at a Solution
alpha is 16.26 using arccos. using s=ut+1/2at^2 equation given, I use, 3.675 = 9.8t - 4.9t^2.
Then I use the quadratic formula (-b+-sqrt...ect) which comes out with t as 2.327s approx.
(When I did this, didn't think this was correct as the path is parabolic, so there are two points of the height 3.675m above O).
I find the horizontal vel. using 35cos [tex]\alpha[/tex] = 33.6. so, using s=ut, i do 33.6x2.327... = 78.05.
This is all wrong apparently according to the mark scheme (attached). I don't understand the mark scheme.
Help! Thanks!