8. A 25 kg sled is pulled across a horizontal surface by a 200 N force at a constant velocity. What is the coefficient of friction between the sled and the surface?

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.

the maxium height is 34m/s

find the sum of the two horizontal vectors and the sum of the two vertical vectors

isoceles right angled triangle

3. dark matter

empty space could also be a simple vacuum