Question

A jet airplane traveling at a speed of $500km/h$ ejects its products of combustion at the speed of $1500km/h$ relative to the jet plane. What is the speed of the latter with respect to an observer on the ground?

• A. $-1000km/h$
• B. $1000km/h$
• C. $100km/h$
• D. $-100km/h$

Answer 1

The correct option is A $-1000km/h$

Given,

Speed of jet with respect to latter, $v_{jl}=500km/h$

Speed of latter with respect to jet, $v_{lj}=-1500km/h$

Speed of the latter with respect to the ground is,

$v_{lg}=v_{jl}+v_{lj}$

$v_{lg}=500+(-1500)$

$v_{lg}=-1000km/h$

The correct option is A.