A steam catapult applies a very large force to supplement the engine thrust of a jet fighter as it takes off from an aircraft carrier. The jet has a mass of 4000 kg and must reach its take off speed of 70 m/s at the end of the 220 m flight deck. What is the combined force of the catapult and engines? (Use the work-energy theorem)

You want to move a heavy box with mass 30.0 kg across a carpeted floor. you pull hard on one of the edges of the box at an angle 30∘ above the horizontal with a force of magnitude 240 n, causing the box to move horizontally. the force of friction between the moving box and the floor has magnitude 41.5 n . what is the box's acceleration just after it begins to move