Answer:
a) 
b) 
c) 
Explanation:
the gravitational potential energy is given by:
The kinetic energy is given by:
the initial kinetic energy is zero because the motion started from rest, so:
applying the conservation of energy theorem:
The work done by the friction force is given by:
the angle of the force is 180 degrees because it's against the movement:
And because of gravity it falls back down to the earth.
Answer;
D. rocket engines are not dependent on oxygen from the air.
Explanation;
-Jet engines and rockets work on the same principle. They produce thrust through an internal pressure difference and, as explained by Newton’s Third Law of Motion, eject exhaust gases in an equal and opposite direction.
-The main difference between them is that jets get the oxygen to burn fuel from the air and rockets carry their own oxygen, which allows them to operate in space.
Additionally, Jet engines have two openings (an intake and an exhaust nozzle). Rocket engines only have one opening (an exhaust nozzle).
Answer:
(3) The electrons are attracted to the positively charged nucleus.
(4) Positively charged protons are located in the tiny, massive nucleus.
(6) The negatively charged electrons are spread out in a "cloud" around the nucleus.
Explanation:
An atom is the basic particle in which a matter is formed. It can either be charged or neutral. When it losses or gains an extra electron, it becomes charged, an ion. While a neutral atom is an atom which has no charge, because it has the same number of electrons and protons. The protons are located in the tiny massive nucleus of the atom, while the electrons are in orbits or cloud around the nucleus.
