posted by suzy .
an ultralight plane had been flying for 40 min when a change of wind direction doubled its ground speed. the entire trip of 160miles took 2h. how far did the plane travel during the first 40 min?
Let V be the initial ground speed and 2V be the final ground speed, in miles per minute.
The length of time travelled at the higher speed was 120 - 40 = 80 minutes
Total distance travelled =
160 = 40 V + 80*(2V) = 200 V
V = 0.8 miles/minute
Inital distance travelled at velocity V = 0.8 miles/min* 40 min = 32 miles
Final distance travelled at velocity 2V = 80*1.6 = 128 miles