00:01
Find the launch speed required for bart such that art and bart collide in mid -air.
00:08
Okay, so for part a, we can write an expression for our height.
00:14
For art, our height is v1yt minus one -half gt squared.
00:20
So our height is going to be 60 times sine of 30 degrees times t minus one -half gt squared.
00:28
Now for bart, we have our height equal to v2 times sine.
00:33
Of 60 degrees t minus one half gt squared so we set these both equal to each other we get v2 is equal to 60 times sine of 30 degrees divided by sign of 60 degrees which is 34 .6 meters per second now for part b how far horizontally will they collide now for part b we want to find our collision time for art we have s1 in the xx direction is equal to v1x t, which is just 60 times cosine of 30 degrees times t.
01:14
And for bart, we get 34 .6 times cosine of 60 degrees times t.
01:23
But our length is equal to these two additions.
01:27
So we set 30 equal to 60 cosine of 30 degrees plus 34 .6 cosine cosine cosine 60 times t.
01:38
So we find t to be 0 .43 seconds.
01:42
So now plugging them back in, we can find s1 equal to 22 .5.
01:49
So it's going to be 22 .5 meters horizontally from our its initial position.
01:55
For a vertical height, our height is then equal to 60 times sine of 30 degrees times our time, which is 0 .43, minus 1 1⁄2 times 9 .8, 0 .5 squared, which is equal to 11 .8 meters vertically.
02:16
Now for our part c, we'd like to find arts velocity and barts velocity.
02:23
So for art, our v final for art is going to be equal to uy minus g t or our 60 times sine of 30 degrees minus g times t, which is 25 .8.
02:39
And so the velocity of art before a collision, is equal to our 52 degrees i -hat plus 25 .8 degrees j -hat...