In track races, especially the longer races, the runners start staggered, which means that they each start at their own starting point, not at the beginning race. This is to make sure that each runner is running the same distance. If the runner in the second lane begins 7 m ahead of the first runner and runs to the 407 m mark and takes 50.0 seconds, what is the runner's speed?

l dont know l am s sorry

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.