space probe Pioneer 11 was lanced April 5, 1973, and reached Jupiter in Dec.1974 traveling a distance of 998 km. How long did it take an electromagnetic signal to travel to earth from pioneer 11 when it was near jupiter?
I believe you have made a typo. Surely it is further than 998 km from earth to Jupiter.
Lets take the worst case using the aphelion distance of 816,500,000 km (I have no idea where 998 km comes from - closest approach of Pioneer 11?)
Speed of light is 299,800,000 m s^-1 or 299,800 km s^-1
so time taken for signal to reach Earth (note capital letter for a planet) is
816,500,000 km / 299,800 km s^-1
To calculate the time it took for an electromagnetic signal to travel from Pioneer 11, we need to first find the distance between Jupiter and Earth. Pioneer 11 was approximately 998 million kilometers away from Earth when it reached Jupiter.
The speed of light in a vacuum is approximately 299,792 kilometers per second. Since electromagnetic signals travel at the speed of light, we can divide the distance between Jupiter and Earth by the speed of light to find the time it took for the signal to travel.
998,000,000 km / 299,792 km/s = 3327.96 seconds
Therefore, it took the electromagnetic signal around 3327.96 seconds to travel from Pioneer 11 to Earth when it was near Jupiter.
To convert seconds into a more familiar unit of time, we can divide by 60 to get the number of minutes:
3327.96 seconds / 60 seconds = 55.47 minutes
So, it took approximately 55.47 minutes for the electromagnetic signal from Pioneer 11 to reach Earth when it was near Jupiter.