Round trip distance/rate problem

Question

Each week, Angela flies her small plane 500 km from Lethbridge to Moose Jaw.  After a brief stopover, she returns to Lethbridge.  On both trips, the air speed is 180 km/h.  On the flight out there is a constant 20 km/h tail wind, and on the return trip a constant head wind of the same speed.  Calculate the time needed for a round trip.

 

 

I cannot get the right answer. Help would be appreciated

Answer 1

Hi Gnarls

 

Its a question on relative speed

Relative speed while going from Lethbridge to Moose  = 180 + 20 =200km/hr

 

Relative speed in reverse direction  = 180-20 = 160 km/hr

 

Time for forward journey = Distance / Effective speed speed  = 500/ 160 = 3.125 hr

For reverse direction Time = 500/200 = 2.5 hrs

Total time = 3.125 +2.5 = 5.625 hr  = 5 hr 37 min and 30 sec

Here the stopping time gas been ignored, so the result is approximate