Calculating speed of free fall object

Question

do i use this formula h=0.5gt² ?

Given height is 9144mm (30,000ft) Given weight is 60kg

how do I find the speed of falling? and time taken to reach the ground.

Answer 1

v=dh/dt=gt h=1/2(gt^2) so gt=(2h/g)^1/2=v now calculate

Answer 2

Is a example of free fall, in this the equation of movement is given by: $$h(t)=h(0)-\frac{1}{2}gt^2$$ When $h(0)$ is the height. And the velocity is given by: $$v(t)=-gt$$

So if you need to know when $h(t)=0$ to find the time and then replace in the equation of the velocity to find your result.

But there is a one tricky equation!

$$v^2(t)=-2g(h(t)-h(0))$$

Which make all more easy

Answer 3

Your formula is correct assuming 1) you start at $h=0, t=0$ 2)you start at rest 3)$h$ is measured downwards. Usually $h$ is measured upwards, so there should be a minus sign. In that case you just set $h=9144$ and solve for $t$.