What element is created when hydrogen atoms fuse together in the sun’s core?

It's Helium.

Explanation:

The superficial layers of the star compress the core as an effect of its own gravity. Therefore, atoms will be closer to each other in the core, allowing them to be combined.

A nuclear reaction occurs when light elements combine into heavier elements (that is known as nucleosynthesis). Different ways in which that can happen exist, but the most common in the Sun, according to its mass, is the Proton-Proton chain reaction. In that fusion reaction two atoms of Hydrogen are combined to form Helium.

Remember that a Helium atom is composed of two Protons and two Neutrons.

The Proton-Proton chain works in the following way:

+ = + +

Two Protons combine each other () and one Deuterium ()  is gotten, and one Neutrino (), and one Positron () are emitted from them.

+ = +

A deuterium and Proton combine each other and a Helium three nucleus() is gotten, and a gamma ray () is emitted.

+ = + +

Two Helium three nucleus combine and a Helium atom  () is gotten, and two Protons are emitted.

So, when hydrogen atoms fuse together helium is created.

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

dang that balls went far