As a spacecraft approaches a planet, the rocket engines on it are fired (turned on) to slow it down so it will go into orbit around the planet. The spacecraft's mass is 2,425 kg and the thrust (force) of the rocket engines is 385 N. If its speed must be decreased by 1,159 m/s, how long (in minutes) must the engines be fired? (Ignore the change in the mass as the fuel is burned.)

Question

Physics

Franklin Moyer

8 October, 20:37

As a spacecraft approaches a planet, the rocket engines on it are fired (turned on) to slow it down so it will go into orbit around the planet. The spacecraft's mass is 2,425 kg and the thrust (force) of the rocket engines is 385 N. If its speed must be decreased by 1,159 m/s, how long (in minutes) must the engines be fired? (Ignore the change in the mass as the fuel is burned.)

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Shaw · Answer 1

121.67 minutes

Explanation:

F = 385N

m = 2425kg

V = 1159m/s

t = ?

Force (thrust) = mass * acceleration

But, acceleration = velocity (speed) / time

a = v / t

F = (m * v) / t

F * t = m * v

t = (m * v) F

t = (2425 * 1159) / 385

t = 2810575 / 385

t = 7300.19 s = 7300.19 / 60 = 121.67 minutes