Robert has just bought a new model rocket, and is trying to measure its flight c

Question

Robert has just bought a new model rocket, and is trying to measure its flight characteristics. The rocket engine package claims that it will maintain a constant thrust of 11.1 N until the engine is used up. Robert launches the rocket on a windless day, so that it travels straight up, and uses his laser range-finder to meaure that the height of the rocket when the engine cuts off is 21.2 m. He also measures the rocket's peak height, which is 25.7 m. The rocket has a mass of 0.663 kg. There are two non-conservative forces which act on the rocket, the thrust force and the drag force, while there is just one conservative force, that of gravity.

Use the relationship ?(TME) = WorkNC to determine how much work is done by the drag force on the rocket during its ascent. (Hint: You need to include the work by both the thrust force and the drag force in WorkNC .)

Explanation / Answer

force x distance = work done by rocket engine
PE gain = mgh

work done by rocket engine - PEgain = work done by drag forces

(11.1 x21.2) - 0.663 (9.8)25.7 = work done by drag forces

work done by drag forces = 68.33682J

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