3.5 Calculating Energy

Work & Energy

Kinetic Energy

At this point we already know that kinetic energy is the energy of motion.

If an object has both mass and velocity, then it has kinetic energy.

We can calculate the kinetic energy of an object using:

begin mathsize 28px style E subscript k space equals space 1 half m v squared end style
Where,
  • m = mass of object (in kg)
  • v = velocity of object (in m/s)
  • Ek = kinetic energy (in Joules)

Energy in Lightning
A single lightning bolt unleashes the same energy as blowing up a ton of TNT.  Every day there are over eight million lightning strikes across the world. With the onset of global warming, that's expected to continue to rise. Each bolt superheats the air around it to about 54,000 degrees Fahrenheit - five times hotter than the sun.  Maybe someday we'll learn how to harness this energy.