I love to split firewood, mainly for exercise, but I wanted to know how much energy I'm burning with each swing. I'm trying to find out if the method I'm using to figure this out is correct. I designed an electronic device with infrared sensors that are one foot apart. As I swing the sledge hammer to split the wood, it goes passed the first sensor which starts a timer that measures in ten-thousanths of a second. When it passes the second sensor it stops the timer. The timer now contains the total time that the sledge hammer took to travel one foot. If I take the reciprocal of this time I have the velocity in feet per second that the sledge hammer was traveling. The sledge hammer weighs 16 pounds. So it has a mass of m=W/32=16/32=0.5 slugs. Now if I apply the formula for Kinetic Energy which is K.E.=(mv^2)/2. This now gives me the total energy that the sledge hammer had at impact. Since the sledge hammer started at rest, then I gave it 100% of this energy. If I convert this energy in foot-pounds into calories by multiplying it by the conversion factor 0.3239, this should give me the total calories I burnt during this one swing. Is this method correct or am I doing something wrong and misapplying physics?