1. in 1989 the spacecraft voyager I passed the planet pluto , and headed out of our solar system , pluto is about 4.6 billion km form earth . as it left the solar system . voyager I was wtill sending radio signals (which travel at the speed of light ) back to astronomers , how many minutes did it take the radio signals from voyager I to get back to earth?
2.our fastest spacecraft are able to travel at 112000km/hour . how long would it take such a spacecraft to travel a distance equal to on light year?
3. telephone companies now use light to send phone conversations over fiber optic cables , suppose you were talking to someone on the other side of the planet , say in japan , about 19200km away , how long would it take the light signal to get there?
谢谢。