Suppose a spacecraft orbits the moon in a very low, circular orbit, just a few hundred meters above the lunar surface. the moon has a diameter of 3500 km, and the free-fall acceleration at the surface is 1.6m/s2. how fast is this spacecraft moving?
a. 53 m/s
b. 75 m/s
c. 1700 m/s
d. 2400 m/s

Spacecraft will be moving in 1700 m/s.

Option C

The diameter of the moon is 3500 km and the free fall acceleration at the surface is given as  

The radius will be half of the diameter of the moon that can be written as:  

By the application of the equation for orbit speed, we get  

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.

i think the answer is a and b

i wish you luck