Earth exerts a downward gravitational force of 8.9 n on a cake that is resting on a plate. the plate exerts a force of 11.0 n upward on the cake, and a knife exerts a downward force of 2.1 n on the cale.

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.

3. dark matter

empty space could also be a simple vacuum