A stone is projected from a point O on a cliff with a speed of of 20ms^-1 at an angle of elevation of 30. T seconds later the angle of depression of the stone from O is 45. Find the value of T.(adsbygoogle = window.adsbygoogle || []).push({});

I assumed that when the stone is at depression of 45 degree to O, it has reached the horizontal plane again, hence displacement is 0. so I used s = ut + 0.5at^2.

s=0

a=-9.8

u=20sin30

therefore t= 2.04, which is apparabtly wrong.

Please help.

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# Assistance with Projectiles

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