Asoftball is hit high into the air. as it rises, the softball
a) loses kinetic energy and loses potential energy.
b) loses kinetic energy and gains potential energy.
c) gains kinetic energy and gains potential energy.
d) gains kinetic energy and loses potential energy.

Answer : The softball loses kinetic energy and gains potential energy.Explanation :

Mechanical energy is the sum of the potential energy and the kinetic energy.

Kinetic energy of an object is possessed by virtue of its motion.

Potential energy of an object is possessed by virtue its height under the action of gravity.

When the softball is hit high into the air. As it rises, the softball loses kinetic energy and gains potential energy. Hence, the total energy remains constant.

Hence, the correct option is (b).

probably not if net force is zero

russian is not my first language, so i'm afraid i can't write out an answer in russian, but hopefully you can find a way to do so. here's my best translation of the problem: you're given a plot of a particle's position in one-dimensional space over time, and you're asked to find either the total distance traveled by the particle after 6 seconds had elapsed, or the total displacement of the particle after 6 seconds.

if you want the total distance traveled, you would first need to determine the particle's velocity as a function of time, then integrate that over the 6-second interval. we know the position function is quadratic with roots at 0 and 6, so we have

where is unknown. because the position is parabolic, there is symmetry about the midpoint at , and we know that

so that the position function is

which means the velocity is

then the total distance traveled is

so the total distance traveled is 20 m.

on the other hand, if you want to find displacement: the particle starts at and ends at , so its displacement is 0.