Just for Njosh

170BFA17HW2.docx

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Q1. The SR-71 Blackbird was a high-speed reconnaissance aircraft built in the 1960’s. It holds the record for the fastest jet-powered aircraft. On July 28th, 1976, an SR-71 flew at 2,193.2 mi/hr (3,529.6 km/h) - a speed record that still stands today.

The SR-71 was powered by two Pratt & Whitney J58-1 turbojet engines and each produced a thrust of 34,000 lb. At takeoff, the mass of the aircraft was 78,000 kg.

Lockheed SR - 71A

Answer the following questions.

a.) How much total thrust is produced by the engines on this aircraft? Give your answer in pounds (lb)

b.) Convert the total thrust of this aircraft to Newtons (N). Use the table from Lecture 5.

c.) At takeoff, what is the acceleration of this aircraft? Use Newton’s Second Law to figure out your answer.

Q2. Let’s say an astronaut has a mass of 75 kg (kilogram). What would this astronaut’s weight be on the following planets/satellites? Note that g is the gravitational acceleration constant. a.) Earth (g = 9.81 m/s2)

b.) Venus (g = 8.87 m/s2)

c.) Mars (g = 3.70 m/s2)

d.) Jupiter (g = 24.5 m/s2)