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.

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.