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Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
A satellite in a circular orbit rotates around the Earth eve
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05 Aug 2019, 09:40
05 Aug 2019, 09:40
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Question Stats:
42% (01:27) correct
57% (00:48) wrong based on 14 sessions
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A satellite in a circular orbit rotates around the Earth every 120 minutes. If the Earth’s radius is 4000 miles at sea level, and the satellite’s orbit is 400 miles above sea level, approximately what distance does the satellite travel in 40 minutes?
A. 1400 miles
B. 9210 miles
C. 4400 miles
D. 4120 miles
E. 8000 miles
A. 1400 miles
B. 9210 miles
C. 4400 miles
D. 4120 miles
E. 8000 miles
Re: A satellite in a circular orbit rotates around the Earth eve
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06 Aug 2019, 05:05
06 Aug 2019, 05:05
No explanation?
The at sea level and above sea level kind of muddles my understanding, can someone clarify that?
The at sea level and above sea level kind of muddles my understanding, can someone clarify that?
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: A satellite in a circular orbit rotates around the Earth eve
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06 Aug 2019, 05:43
06 Aug 2019, 05:43
GreenlightTestPrep wrote:
A satellite in a circular orbit rotates around the Earth every 120 minutes. If the Earth’s radius is 4000 miles at sea level, and the satellite’s orbit is 400 miles above sea level, approximately what distance does the satellite travel in 40 minutes?
A. 1400 miles
B. 9210 miles
C. 4400 miles
D. 4120 miles
E. 8000 miles
A. 1400 miles
B. 9210 miles
C. 4400 miles
D. 4120 miles
E. 8000 miles
This diagram might help
So, the black dot represents the Earth's center.
So, the radius of the satellite's orbit = 4400 miles
circumference of circle = 2πr
So, the circumference of satellite's orbit = 2π(4400) = 8800π
GIVEN: the satellite in a circular orbit rotates around the Earth every 120 minutes.
In other words, the satellite travels 8800π every 120 minutes
So, in 40 minutes, the satellite will travel 1/3 of the 8800π mile orbit (since 40 minutes is 1/3 of 120 minute)
Distance traveled = 8800π/3
PRO TIP: Since π ≈ 3.14, we know that π/3 ≈ 3.14/3 ≈ some number a little bit bigger than 1
So, 8800π/3 = 8800(π/3) = 8800(a number a little bit bigger than 1) = some number a little bit bigger than 8800
Answer: B
Cheers,
Brent
