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? | Learn NCERT solution | Education portal Class 11 Physics | Study online Unit-3 Motion In A Straight Line





Q.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 ?

 

Answer:-
Speed of the jet airplane, vjet = 500 km/h

Relative speed of its products of combustion with respect to the plane,
vsmoke = – 1500 km/h
Speed of its products of combustion with respect to the ground = vsmoke
Relative speed of its products of combustion with respect to the airplane,
vsmoke = vsmokevjet
– 1500 = vsmoke – 500
vsmoke = – 1000 km/h
The negative sign indicates that the direction of its products of combustion is opposite to the direction of motion of the jet airplane.