Physics question

Ph2A Win 2020 Homework Project No.2

Max Yuen

Feb 2020

Problem 1: Armageddon Part I: Year 2320 An asteroid is on an impact course to strike the earth! A piece broke off and is traveling toward your favorite coastal city (insert name of city here). Initial calculations show that the object will strike at a angle of inclination of 60 degrees with a terminal speed of 10000m/s. The trajectory is nearly straight. You have been tasked to save the city. You need to devise a plan to intercept it. You have 10 hours before the asteroid enters the stratosphere ( 50km above ground). Here are a few choices. Discuss each one.

1. Use the Rail Gun, but you’ll need to hit it a few times. It takes about 6 seconds to reload and fire again. Likely it will need at least 3 shots. This will be fired from a naval destroyer about 10km offshore. Muzzle velocity is 4.3 km/s. Do you need more ships? Just ask or negotiate with your favorite allies.

2. Use an ICBM tipped with some high explosives (or a low yield nuclear device) to intercept the object in outer space. The initial boost stage will put the rocket at about 150km from the surface of the earth with about 7km/s speed. Luckily, you can fire this from a submarine. It’s ready to go in 30 minutes. Just say the word.

3. Evacuate the city now. There’s no hope! Why didn’t they see it sooner? It was behind the moon and just emerged with less than 10 hours for the anyone to react.

4. That’s just the small piece. Stay tuned for part II.

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Problem 2: Mystery of Test Flight SB530 You have been tasked to investigate the tragic accident of Test Flight SB530, which is an unmanned self-piloting aircraft. There are two theories surrounding the circumstances of this accident. Some say it’s software malfunction and the plane simply crashed. Others say it exploded in mid-air, but don’t know why. All we know is that the radio communication with plane was lost somewhere over the Mojave Desert moments before the plane went down. Here’s what we know:

1. The plane was about 10.4 km above the desert heading due North, bearing 31.5 degrees. (31.5 degrees measured from North.)

2. The plane was cruising at this altitude at 560mph before all communications was lost.

3. A debris field was found with many pieces scattered around. The center of the debris field was located at about 5 to 8 km from the last known location of the plane.

4. The radius of the debris field is the curious anomaly. It’s much larger than you expected.

You must now make two estimations.

1. CASE 1: The plane exploded after it hit the ground, sending the parts flying from a single point of impact in all directions. You assume that average speed of the flying parts is about 400-500m/s, and can be shot out in any direction out of the ground.

2. CASE 2: The plane exploded in mid-air. The parts again are flying all over the place but you include the initial velocity of the plane.

Estimate the size of the debris field and make a comment about what might have happened? Note that you will not need to use air resistance or drag, so your estimates are much larger than it would be. The trend, however, is the important idea here.

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