The process by which planets form when material orbiting some stars starts gathering together through collision and gravitation and electrostatic attraction is called a) accretion b) nuclear fusion c) differentiation d) strong nuclear force

A) accretion

Explanation:

Accretion is the growth of a body by aggregation of matter. This is a process of accumulation of particles in a massive object gravitationally attracting more matter, typically gaseous matter, in an accretion disk.

It should be noted that this theory was proposed by Russian geophysicist Otto Schmidl in 1944 and explains that most of the objects in the universe, such as galaxies, stars and planets, are formed by accretion processes. A good example of this is the accretion of mass by a star that is given by the addition of mass to the star from interstellar matter or a neighbor star.

can be answered using momentum.

momentum = p

p1= mass1 * velocity1

p1 = p2

therefore

p1 = 6kg * 4m/s

p1 = 24kgm/s

p2=m2 * v2

24 kgm/s = 7kg * v2

v2 = 24 kgm/s / 7kg

v2= 3.42 m/s