# Thread: antiderivative world problem

1. ## antiderivative world problem

A stone is dropped from the top of a 450 m tower. (Acceleration due to gravity is -9.8 m/s2. Ignore air resistance. Give your answers correct to two decimal places.)

(a) Find the distance of the stone above ground level at time t.
$\displaystyle s(t)=$$\displaystyle 450 - \frac{9.81t^2}{2} (b) How long does it take the stone to reach the ground? \displaystyle 0 = 450 - \frac{9.81t^2}{2} \displaystyle t = \sqrt\frac{(2 * 450)}{ 9.81} =\displaystyle 9.58 sec. (c) With what speed does it strike the ground? This is the part I keep getting wrong. \displaystyle v(t)=-9.8t =\displaystyle -9.8(9.58) =\displaystyle -93.97 2. Originally Posted by hazecraze A stone is dropped from the top of a 450 m tower. (Acceleration due to gravity is -9.8 m/s2. Ignore air resistance. Give your answers correct to two decimal places.) (a) Find the distance of the stone above ground level at time t. \displaystyle s(t)=$$\displaystyle 450 - \frac{9.81t^2}{2}$

(b) How long does it take the stone to reach the ground?

$\displaystyle 0 = 450 - \frac{9.81t^2}{2}$

$\displaystyle t = \sqrt\frac{(2 * 450)}{ 9.81}$
=$\displaystyle 9.58 sec.$

(c) With what speed does it strike the ground? This is the part I keep getting wrong.

$\displaystyle v(t)=-9.8t$
=$\displaystyle -9.8(9.58)$
=$\displaystyle -93.97$
speed is a scalar > 0