# >> K-12 >> K-12 For Educators

How to Calculate the Cutting Force of an Axe on a Log

An axe maximizes its cutting force, the force that splits a log, by concentrating the force along a narrow cutting area. The weighted design of an axe allows the user to generate a huge amount of force by rapidly accelerating the axe head. Sir Isaac Newton first described the laws of motion that allow you to calculate the cutting force of an axe applied to a log. Presenting students with the example of a person splitting firewood provides a way for students to engage some fundamental physics calculations using a real world example.

Instructions

- 1
  Take the weight of the axe head. Record the weight in kilograms. Divide the weight in pounds by 2.2 to convert to kilograms.
- 2
  Record the velocity of the axe right before it makes contact with the log. Use an accelerometer if available. Divide the distance from the top of the swing -- as the person holds the axe above his head -- to the top of the log, in meters, by the time, in seconds, it takes the person to swing. Record the result as the velocity.
- 3
  Multiply the weight of the axe head by the velocity of the swing squared. For example, an axe weighting 2 kilograms swinging at 2 meters per second has a force of 8 kilogram-meters per second squared, also known as Newtons.
- 4
  Measure the cutting area of the blade in meters. Multiply the length by the width. For example, a cutting blade that is 500 millimeters long by 20 millimeters wide has a cutting area of 1000 millimeters, or 1 meter.
- 5
  Divide the force of the swing in Newtons by the cutting area of the blade in meters. Record the result as the cutting force of the axe on the log in Pascals. For example, 8 Newtons divided by 1 meter equals 8 Pascals of cutting force.

7th Grade Earth Science Topics for Papers

Fun Games Teaching Children Spanish