Speed of waves and time delay question

[kirsten_2009]

Homework Statement

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What is the time delay for a television signal that is sent via satellite? Communications satellites orbit above the equator in circles of radius 36,000 km (6 times larger than Earth’s radius!).

Not sure if my answer is correct...

Homework Equations

time=distance/speed

The Attempt at a Solution

Not sure how satellite signals work but I assume that they operate on the surface of the Earth and that the signal travels to the Earth’s surface and back to the satellite…so the actual distance would be 36,000 km – 6,000 km (the distance from the center of the Earth to the surface) = 30,000 km x 2 (round trip) = 60,000 km.

time = distance / speed = 60,000 km / 3x10⁵ km/sec = 0.2 sec

 

[marcusl]

Your method is sound, but I'd double-check the orbit. 36,000 km is usually quoted as the orbit altitude, making 42,000 km radius from the Earth's center.