Jet Catapult Work: Calculate Kinetic Energy & Work Done

[ayerski]

Homework Statement

A fighter jet is launched from an aircraft carrier with the aid of its own engines and a steam powered catapult. The thrust of its engines is 2.3x10^5 N. In being launched from rest it moves through a distance of 87 m and has a kinetic energy of 4.5x10^7 at lift off. What is the work done on the jet by the catapult

Homework Equations

W= Fd
Ek= 1/2mv^2
W= Ekf - Eki

The Attempt at a Solution

It is clear I need to determine the velocity either from the kinetic energy formula or use it in the 3rd formula to determine the total work ad subtract the thrust of the engines, but what's throwing me off is that the mass is not given and it seems i need it to use these formulae.

 

[PhanthomJay]

The final KE is given, so do you need to know the mass? Use your third equation, then what?

 

[kerimek]

I would approach this problem by first clarifying any missing information. In this case, the mass of the jet is not given, which is necessary for calculating kinetic energy. I would reach out to the source of the problem to see if the mass can be provided or if it was accidentally omitted. Without the mass, it is not possible to accurately calculate the work done on the jet by the catapult.

Assuming the mass is provided, I would then use the given thrust of the engines to determine the acceleration of the jet using Newton's second law (F=ma). From there, I can use the kinematic equations to calculate the velocity of the jet at lift off. Once the velocity is known, I can plug it into the kinetic energy formula to determine the kinetic energy at lift off.

To calculate the work done by the catapult, I would use the work-energy theorem (W= Ekf - Eki) where Ekf is the final kinetic energy and Eki is the initial kinetic energy (which is assumed to be zero in this case). This would give me the total work done on the jet by both the engines and the catapult.

In summary, to accurately determine the work done on the jet by the catapult, the missing information of the jet's mass would need to be provided. Once the mass is known, the problem can be solved using the appropriate equations and principles of physics.