We will be using the equation S = ut + 1/2 g t^2
Given S = -1000 m, u = -10 m/s and g = -9.8 m/s^2
Plugging in the information given above, 1000 = 10t + 4.9 t^2
We have a quadratic equation in t as 4.9t^2 + 10t -1000 = 0 t=−b±√b2−4ac / 2a
t=−(10)±√(10)2−4(4.9)(−1000) / 2(4.9)
t= −10±√19700/ 9.8
t=13.301702905732856,
so solving we get t = 13.3 s.
