Q 3.5 A jet airplane travelling at the speed of 500 km h-1 ejects its products of combustion at the speed of 1500 km h-1 relative to the jet plane. What is the speed of the latter with respect to an observer on the ground ?
Vairplane=500 km h-1
Vprod/airplane=-1500 km h-1 (the negative sign signifies the Velocity of the plane and the velocity of the ejected combustion products relative to the plane are in opposite directions)
Vprod/airplane=Vprod - Vairplane
Vprod =Vprod/airplane +Vairplane
Vprod=-1500+500=-1000 km h-1
The speed of the ejected combustion products with respect to an observer on the ground is 1000 km h-1