A spacecraft circling the moon at a distance of 384,000 km from the
earth communicates by radio with a person on earth. How much time
elapses between the sending and receiving of a signal?
Divide the distance by the speed of light, 3.00*10^5 km/s.
To determine the time elapsed between the sending and receiving of a signal from the spacecraft to Earth, we need to calculate the time it takes for the signal to travel the distance between them.
The spacecraft is located at a distance of 384,000 km from Earth, and the signal needs to travel this distance twice (to the spacecraft and back to Earth). Therefore, we need to divide the total distance by the speed of light, which is approximately 299,792 kilometers per second.
Let's calculate the time elapsed:
Distance = 384,000 km (one-way)
Total distance = 2 * Distance = 2 * 384,000 km = 768,000 km
Speed of light = 299,792 km/s
Time elapsed = Total distance / Speed of light
Time elapsed = 768,000 km / 299,792 km/s
Using a calculator, we can find the approximate time elapsed.
Therefore, the time elapsed between the sending and receiving of a signal from the spacecraft to Earth is approximately 2.56 seconds.