A 8.0*104kgspaceship is at rest in deep space. Its thrusters provide a force of 1200kN. The spaceship fires its thrusters for 20s, then costs for 12km. How long does it take the spaceship to coast this distance

Time = 40 s

It will take the spaceship 40s to coast that distance.

Explanation:

Using the impulse momentum equation;

Impulse = change in momentum

Ft = m (∆v) ... 1

Given;

Force F = 1200kN

time of action t = 20s

Mass of spaceship m = 8.0*10^4 kg

∆v = change in velocity

Substituting the values into equation 1;

1200kN * 20s = 8.0*10^4 kg * ∆v

∆v = 1200000*20/80000

∆v = 300 m/s

Since it was initially at rest, V0 = 0

Final velocity V2 = 300 + 0

V2 = 300m/s

Time To travel 12 km,

Time = distance/speed

Distance = 12 km = 12000m

Speed = 300m/s

Time = 12000/300

Time = 40 s

It will take the spaceship 40s to coast that distance.