What equation shows that infinite energy is needed to reach light speed?

[blanenotanewb]

i think F=ma accounts for the gain in force required to accelerate objects as you go faster and faster but this does not explain how objects cannot reach the speed of light.
what equation explains how it takes an infinite amount of energy to get to the speed of light.

 

[russ_watters]

http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/veltran.html

 

[blanenotanewb]

Thank you