Question

56. A satellite of mass "m" is in orbit around the earth. If a second satellite of mass "2m" is to be placed in the same orbit, the second satellite must have a velocity which is a) half the velocity of the first satellite b) the same as the velocity of the first satellite c) twice the velocity of the first satellite d) four times the velocity of the first satellite

Answer 1

spacecraft's engine ejects mass at a rate of 30 kg/s with an exhaust velocity

of 3,100 m/s. The pressure at the nozzle exit is 5 kPa and the exit area is

0.7 m2. What is the thrust of the engine in a vacuum?

SOLUTION,

Given: q = 30 kg/s

Ve = 3,100 m/s

Ae = 0.7 m2

Pe = 5 kPa = 5,000 N/m2

Pa = 0

Equation (1.6),

F = q × Ve + (Pe - Pa) × Ae

F = 30 × 3,100 + (5,000 - 0) × 0.7

F = 96,500 N