Physics

1 Watch the video and put the words into the gaps in the text.

Flying in a 747 from one side of the Earth to the exact opposite side would take about 22 hours… and while I know there’s a bit of rock in the way, that’s really going the long way round. So what if we did dig a hole all the way through the Earth, through the center, and jumped in? Well, Michael, you probably wouldn’t make it very far - that’s because of the Coriolis 1_____ (which is why a ball curves weirdly when you toss it while riding a 2_____ and why hurricanes always spin 3________ in the northern 4______). At the equator, the Earth is rotating eastwards at 1670 km/hr. As you go deeper, the bits of Earth around you are still spinning around once per day, but they don’t have as far to travel so they’re going at slower and slower 5______. If you jumped into a vertical 6_____, you’d soon be traveling east faster than the rock around you so that after falling only a few kilometers, you’d crash into the eastern wall. It might not be a 7______, but some miners near Lake Superior tried to test this by dropping cannon balls down a mile-long shaft - and the balls never reached the bottom. Ok, so what if the tunnel went from pole to pole, so the Coriolis effect didn’t 8______, and let’s also assume that there’s no air resistance, or 9______. Ok. Since the Earth’s mass is more concentrated close to the middle, 10____ would pull you down with roughly the same amount of force for the first 3000 km, or halfway to the center of the Earth - this familiar, constant force would 11 ______ you until you were falling 8 km every second, and the trip halfway to the middle of the Earth would only take 13 minutes. Soon after, you’d reach the Earth’s outer 12 ______, and this is the point in your journey where the pull of gravity would be strongest - but only slightly stronger than the force we’re used to on the 13 ______. As you continued to fall closer to the 14 ______, so much of the Earth’s mass would now be above you that it would begin to seriously cancel out the 15 ______ of the mass below, and the pull would weaken until you reached the center. Here, you’d experience no gravitational pull at all - or rather, the Earth would be pulling on you the same amount in all 16 ______, so you could 17 ______ freely around with no sense of ‘up’ or ‘down’. Except, remember, that you’d be speeding past at 22,000 miles per hour, or 6 miles a second. Once you passed the center, the whole process would 18 ______ and you’d gradually slow, pulled down weakly at first and then more strongly, until when you got to the other side, you’d stop moving and could step out on the surface, a mere 37 minutes, or one dryer cycle, later. Of course, the deepest we’ve ever been able to dig is the Kola Superdeep Borehole in Russia. But it only went down 12 km, which is only two thirds the length of Manhattan. They had to stop because it got too 19 ______: 180°C. And this is sort of the problem with digging a hole through Earth - Earth is hot, and 20 ______  in the middle. You can’t just dig a hole through it with shovels. But here is a question: wasn’t the middle of Earth wasn’t all ‘liquidy’, what if Earth was 21 ______, but weighed the same? Well, with its entire 22 ______  concentrated in a thin shell right under our feet, the Earth wouldn’t have a 23 ______  field any more, because that comes from the molten 24 ______  core. So we’d be totally 25 ______  to radiation from the solar wind and storms, and this means we’d see the 26 ______  everywhere. Look! The Northern-Southern-Eastern lights! And if you jumped inside the hollow Earth to escape the solar storm? Well, 27 ______ from the different parts of the 28 ______ Earth-shell would perfectly cancel out and you’d float freely about inside as if the Earth weren’t there at all! Of course, you’d better bring a 29 ______ suit, because there’s not nearly enough air ON Earth to fill up the entire INSIDE of Earth. But what if the entire inside of the hollow Earth were covered with mirrors? Henry, that’s ridiculous… for now. Ok, so back outside of the Earth, we wouldn’t really notice much difference from a gravitational 30 ______ - falling things would still accelerate at 9.8 m/s2, a baseball would follow the same 31 ______, and the moon would follow the same orbit around the Earth. Hey, Henry. Let’s go to outer space, right now. Bring your gun - this’ll all make sense later. C’mon.
	shaft
	merry-go-round
	disaster
	counterclockwise
	effect
	speeds
	hemisphere
	friction
	apply
	core
	attraction
	accelerate
	float
	directions
	gravity
	reverse
	surface
	center
	magnetic
	vulnerable
	hollow
	hot
	aurora
	molten
	mass
	iron
	spherical
	space
	gravity
	trajectory
	perspective

2 Vocabulary focus. Sudy the wordsand  word combinations, practise their translation, spelling. Check your knowledge in the test. Play vocabulary game and set your own vocabulary game record.

 

3 Mark the following statements as True or False.

1.            The bits of Earth around you are going at slower and slower speeds. 

2.            The balls always reached the bottom, if they were dropped down a mile-long shaft.

3.            The Coriolis effect doesn’t apply to the falling objects.

4.            The Earth’s mass is more concentrated close to its middle.

5.            If the middle of the Earth had no air resistance, no friction; the result of passing through its center would be gradual acceleration.

6.            Digging Kola Superdeep was stopped because it was too cold.

7.            The Earth wouldn’t have a magnetic field anymore if Earth was hollow, but weighed the same.

8.            If the Earth was hollow people wouldn’t really notice much difference from a gravitational perspective.

9.            People wouldd be totally invulnerable to radiation from the solar wind and storms, if Earth was hollow, but weighed the same.

10.       Hurricanes always spin counterclockwise in the southern hemisphere.

4 Answer the Questions.

1.       What would happen if Coriolis effect didn’t apply and the tunnel through Earth went from pole to pole?

2.       How long would the trip halfway to the middle of the Earth take without air resistance, or friction?

3.       What is the deepest borehole?

4.       What is the problem with digging a hole through the Earth?

5.       Under what circumstances would people be able to see the aurora everywhere?