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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 3.96 x 105 N. In being launched from rest it moves through a distance of 85.0 m and has a kinetic energy of 7.68 x 107 J at lift-off. What is the work done on the jet by the catapult?

2007-03-02 13:14:29 · 2 answers · asked by Mariam T 1 in Science & Mathematics Physics

2 answers

The given total kinetic energy is the result of work done by the thrust of the engines and by the catapult. So if we know the work done by the thrust of the engines and deduct it from the kinetic energy at lift-off, we get the work done by the catapult. In other words,

Work done by thrust of engines+Work done by catapult=
Total kinetic energy.

Work done by thrust of engines=3.96*10^5*85
=3.37*10^7

Substitute known values:

3.37*10^7+Work done by catapult=7.68*10^7

Work done by catapult=7.68*10^7-3.37*10^7
=4.31*10^7 joules

2007-03-02 18:53:20 · answer #1 · answered by tul b 3 · 0 0

Work done by catapult = 4.314 x 10^7 joules

The work done by the engines is equal to Force x Distance

W (engine) = FD = 3.96x 10^5 x 85.0 = 3.366 x 10^7 joules

The total energy is equal to the kinetic energy = 7.68 x 10^7 joules

Total Energy = Work (engine) + Work (catapult)

7.68 x 10^7 = 3.366 x 10^7 + Work(catapult)

Work (catapult) = 4.314 x 10^7 joules.

2007-03-02 14:54:53 · answer #2 · answered by ignoramus_the_great 7 · 0 0

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