Force Calculation: Incorrect Result

[Alexandra Fabiello]

Homework Statement

Jet fighter planes are launched from aircraft carriers with the aid of their own engines and a catapult. If in the process of being launched from rest, the thrust of a jet's engines is 2.10 * 10^5 N and after moving through a distance of 90 m the plane lifts off with a kinetic energy of 4.20 * 10^7 J, what is the work done on the jet by the catapult?

Relevant Equations

Work total = change in kinetic energy
force = change in kinetic energy / change in distance

force = 4.2e7 J/90 m = 466666.6667 N
this minus 2.10e5 = 2.57e5 N rounded
This is incorrect, so I'm probably missing a formula or something.

 

[haruspex]

Homework Statement: Jet fighter planes are launched from aircraft carriers with the aid of their own engines and a catapult. If in the process of being launched from rest, the thrust of a jet's engines is 2.10 * 10^5 N and after moving through a distance of 90 m the plane lifts off with a kinetic energy of 4.20 * 10^7 J, what is the work done on the jet by the catapult?
Homework Equations: Work total = change in kinetic energy
force = change in kinetic energy / change in distance

force = 4.2e7 J/90 m = 466666.6667 N
this minus 2.10e5 = 2.57e5 N rounded
This is incorrect, so I'm probably missing a formula or something.

You are asked for the work done, not the force.

 

[Alexandra Fabiello]

You are asked for the work done, not the force.

Whoops, I mixed up 'change in kinetic energy' with force somehow.

Thanks, that worked!