00:01
All right, it took me a while to figure out what was going on here, but i think i've figured it out.
00:10
I'm going to call this the z direction.
00:15
This into the paper is the y direction, and then this is going to be the x direction.
00:23
Now, there's a missile being fired from 5 ,000 meters away.
00:36
And it is fired at a 20 degree angle at 600 meters per second.
00:53
Now, the anti -ballistic missile is being fired from 500 meters away.
01:03
And it's being fired in the yz plane at 60 degrees to the y within the yz plane, with an initial velocity of v sub -zero.
01:25
All right.
01:27
Now, using this, which took me a long time to figure out what it meant, using this, then i thought about is the rocket, the original rocket aiming for the target, aiming for zero, the origin in this case? so i have the equation that i've used before.
01:50
The range is v initial squared, sine squared theta.
02:00
No, no, no, not sine square of theta, sign of two theta.
02:08
Over g.
02:13
Well, the initials 600, sine of 2 times 20 over 9 .81 meters per second squared.
02:27
That gives me 23 ,588.
02:39
So it's aiming in the direction of the origin, but it's not actually going to strike at the origin because it's going to fly 23 ,58 meters, which is much longer than 5 ,000 meters.
02:55
Okay.
02:57
So this missile is going to go over like this.
03:03
Actually, it's going to still be heading upward when it gets to x equals zero.
03:08
So i need to figure out when it gets to x equals zero.
03:13
So i'm going to use x equals x in.
03:19
Plus v initial t plus one half a x t squared this should be v x as well but this is zero there's no acceleration in the x direction so i wanted to reach zero but it starts at 500 um v initial is in the negative direction that would be negative 600 meters per second times the cosine of 20, to put it in the x direction, times t.
04:03
So i know that i can solve this.
04:07
T is going to be 500 over 600 cosine cosine 20.
04:23
That is the time when it needs, the anti -ballistic missile needs to strike the rocket.
04:33
But at that time, t, the height, which i've called z, is going to be z initial, plus vz initial, t minus one -half g t squared.
04:53
So, z at that point, which i don't know what it's going to be, z initial is zero because the missile was fired from the, the ground, vz initial is 600, sine 20, t minus one half.
05:18
Half of 9 .81 is 4 .905.
05:28
Okay, but we know that t is 500 over 600, cosine 20.
05:35
So z is going to be, just going to put that into a calculator, which i think i have around here somewhere.
05:51
There it is.
05:55
Okay, so 600 minus, nope, 600 20, t minus, what am i looking out here? 4 .905 t squared.
06:28
Okay, but t is 500 .050 .0 .0 .0 .0.
06:33
Over 600 cosine 20.
06:38
T is 0 .8868 seconds.
06:49
Let me write that down.
07:01
That seems awfully fast.
07:06
It's going 600 meters per second for 5 ,000 meters.
07:15
Yeah, that doesn't seem right.
07:17
600 meters per second for five.
07:22
Oh, it's going 5 ,000 meters.
07:28
5 ,000 meters.
07:30
Okay.
07:33
So there should be a thousand in there.
07:38
Then this is actually going to give me 8 .8 seconds...