If the speed of light is 3x10^8m/s and the distance around the earth is 4.5x10^4 km and a plane could travel at half a speed of light, how long would it take for the plane to fly around the earth twice?

d = 9 * 10^7 meters

time = distance/speed

= 9 * 10^7 meters/ 1.5 * 10^8 m/s

= 6 * 10^-1

= 0.6 seconds

That sounds like very little
but if you are looking at high frequency radio signals, that can be a huge difference in phase between the wave coming to you and the wave reaching you around the earth :)

Thanks

You are welcome.

but the questions says twice. you have just calculated once.

To determine the time it would take for the plane to fly around the Earth twice, we can follow these steps:

Step 1: Convert the speed of light to km/h:
- Given the speed of light is 3x10^8 m/s.
- To convert m/s to km/h, we need to multiply by 3.6 (since there are 3600 seconds in an hour).
- Therefore, the speed of light is 3x10^8 * 3.6 = 1.08x10^9 km/h.

Step 2: Calculate the speed of the plane:
- Given the plane can travel at half the speed of light.
- Therefore, the speed of the plane is (1.08x10^9) / 2 = 5.4x10^8 km/h.

Step 3: Calculate the time it would take for the plane to fly around the Earth once:
- Given the distance around the Earth is 4.5x10^4 km.
- To find the time, we divide the distance by the speed of the plane.
- Therefore, the time it would take for the plane to fly around the Earth once is (4.5x10^4) / (5.4x10^8) hours.

Step 4: Calculate the time it would take for the plane to fly around the Earth twice:
- Since the plane is flying around the Earth twice, we need to multiply the time it takes to fly around once by 2.
- Therefore, the total time it would take for the plane to fly around the Earth twice is 2 * [(4.5x10^4) / (5.4x10^8)] hours.

By following these steps, you should be able to find the time it would take for the plane to fly around the Earth twice using the given information.