Need help in physics 11

Question

How do I find out what the initial and final velocity is? for ex. A stone tumbles into a mineshaft and strikes bottom after falling for 4.2 secs. how deep is mineshaft. I am confused by which velocity we try to find and which velocity is 0 m/s. Is there any technique in solving word problems we could use to find out which is which (initial and final velocity)

Answer 1

The question is talking about free falling stone. In a free fall Only gravity is acting upon the stone and the initial velocity is 0. Basically, you need to know and use the following equations:

Vf=Vo+ gt, to find the final velocity Vf

d=1/2 gt^2 + Vot, to find the depth of the mineshaft

The acceleration is g=10 m/s^2

t=4.2 s

Vo is the initial velocity, which is 0 m/s

I hope this helps.