physics please be clear with equations Robert has just bought a new model rocket
ID: 2140289 • Letter: P
Question
physics please be clear with equations
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 13.2 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 measure that the height of the rocket when the engine cuts off is 12.4 m. He also measures the rocket's peak height, which is 16.9 m. If the rocket has a mass of 0.763 kg, how much work is done by the drag force on the rocket during its ascent?Explanation / Answer
Upward force = Thrust (till 12.4m) = 13.2 N
Downward force = Drag + Gravity = F + mg = F + (0.763*9.8) = F + 7.48
Net upward force (till 12.4m) = N1 = 13.2 N - ( F + 7.48 ) = 5.72 - F
Net upward force (after 12.4m) = N2 = - ( F + 7.48 )
Work done = N1 * 12.4 + N2 * ( 16.9 - 12.4 ) = 12.4 * (5.72 - F) + 4.5 * ( - F - 7.48 ) = 37.27 - 16.9 F
Work done + Energy gained = 0
37.27 - 16.9 F +mg*16.9 = 0
37.27 +126.37 = 16.9 F
F = 9.68 N ~ Drag Force (downward)
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.