Question

A reconnaissance plane flies 605 km away from
its base at 284 m/s, then flies back to its base
at 426 m/s.
What is its average speed?
Answer in units of m/s.

Answer 1

Answer:

                      $v_{avg}  =$ 355 m/s  

Explanation:

Distance = 605 km

Initial speed = $v_{i}$ = 284 m/s

Final velocity = $v_{f}$ = 426 m/s

Average speed = ?

There is two method two find average speed. In first method, using 3rd equation of motion, we find acceleration.

                        $2as = v_{f}^{2}+v_{i}^{2}$

Then using first equation of motion, we find time

                        $v_{f} = v_{i}+at$

Then using the formula of average velocity, we find average velocity

                         $v_{avg}=\frac{total-distance}{total-time}$

Second method is very simple

                                  $v_{avg}=\frac{v_{f}+v_{i} }{2}$

                                   $v_{avg}=\frac{426+284}{2}$

                                   $v_{avg}  =$ 355 m/s