What is the net force acting on the box

According to Mr. Newton, an object will only accelerate if there is “net force” acting upon it. A net force is the sum of all forces acting on an object. A net force is capable of accelerating a mass.

Explanation:

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.  

answermeridional ;