Question 386394
s= ut*1/2*g*t^2
s= distance
u= initial velocit
t= time
380=20t+1/2*9.8*t^2
380=20t+4.9t^2
4.9t^2+20t-380=0
multiply by 10
49t^2+200t-3800=0
find the roots by quadratic formula
b^2-4ac=784800
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{{{x1=(-200+sqrt(784800))/98}}}
x1=6.998 seconds
7 seconds
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x2 will be negative & time cannot be negative
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m.ananth@hotmail.ca