00:01
All right, so we've got a stone being thrown upwards.
00:04
So v0 is something.
00:08
It passes a point a, and at a, the speed at a is just v.
00:25
And point b, which is three meters higher, so the distance from a to b is three meters meters, okay, and its speed there is one half v, with the speed and height that it reaches.
01:00
Okay, vb squared equals va squared minus 2g, d.
01:19
Therefore, va is v, and vb is one -half v.
01:29
Well, one -half v squared is one -fourth v squared, v squared minus 2 gd.
01:38
So, v minus one -fourth v would be 3 fourth v squared, equals 2 gd.
01:51
So v is going to be the square root of eight -thirds g -d.
02:06
Okay, putting that in a calculator, v equals square root of eight -thirds, g is 9 .81, d is 3.
02:25
So, eight -thirds, g -d.
02:30
Okay, that's going to be 8 .86 meters per second...