A football is thrown a distance of 20 meters. What is the speed of it takes 0.5 seconds to cover the distance?

they are made of gases.

they have a spherical shape.

they make energy through fusion.

1 is the answer to this problem

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.