Question

Please show all work and answer both parts A and B. Thanks

3. An aircraft with a mass of 2,000 kg starts from rest at sea level and takes off, then flies to a cruising speed of 620 km/h and altitude of 10 km. Assume g-9.8 m/s throughout the process What is the aircraft's change in potential energy? What is the aircraft's change in kinetic energy? a. b. Answers: About 200 and 30 M.J, respectively.

Answer 1

change in potential energy is calculated by taking potential energy of aircraft at sea level to be 0 (reference) then

potential energy of aircraft at 10 km altitude = mgh = 2000 x 9.8 x 10000= 196 MJ = 196 x 10⁶ J if we take g = 9.8 m/s²

if we take g = 10 m/s² then change in potential energy = 200 MJ = 200 x 10⁶ J

at sea level speed of aircraft is 0 so kinetic energy = 0 J

at 10 km altitude it's speed = 620 km/hr

so change in kinetic energy = (0.5) x m x v x v = 29660493.83 J = 29.6 MJ = 30MJ

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