1. at which point is the vertical velocity equal to zero? 2.during which part of the projectile's path does velocity increase?

#1

in projectile motion when object reached to the highest point then its velocity in vertical direction becomes zero

So its velocity in vertical direction is zero at POINT B

#2

During first half part of motion ball goes up high in air so its vertical speed will decrease due to gravity

while when it will drop back in next half where its vertical speed will increase

So its speed will increase between point B and C

found in the nucleus

has mass of one amu

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.