Distance from Earth to Pluto

Question

The mean distance to Earth from Pluto is 4.58*10^9 kilometers. The first U.S. space probe to Pluto transmitted radio signals from Pluto to Earth at the speed of light, 3.00*10^5 kilometers per second. How long (in seconds) did it take for the signals to reach earth?

Answer 1

Velocity = the change in distance ÷  the change in time

 

Solving for the change in time yields 

 

the change in distance ÷ Velocity

 

We are given that the Velocity = 3.00*10⁵ kilometers per second, and the change in distance = 4.58*10⁹ kilometers

 

change in time = 4.58*10⁹ kilometers ÷ 3.00*10⁵ kilometers per second

 

change in time = 15267 seconds

 

It took 15267 seconds to get from Earth to Pluto

Answer 2

This is a form of a D-I-R-T (Distance-Is-Rate-times-Time) problem.  That is, D=RT.

 

For this problem, we want to know Time.   So,

                T = D / R

 

Time = (4.58 * 10⁹ km) / (3.00 * 10⁵ km/sec)

        = (4.58/3.00)*10⁴ sec     [notes: km cancel out; 9-5=4]

        = 1.5266*10⁴ sec

        = 15267 sec

 

Note:  This is 254.4 minutes.

This is also 4.24 hours.

This is approximately 4 hours and 14 minutes and 24 seconds.