Karate Lab

# Karate Lab - Relating the Force and Energy of a Closed Fist...

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Relating the Force and Energy of a Closed Fist to the Force and Energy Required to Break a Wooden Board Paul Park Joshua Williams

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Abstract In this experiment, widgets of about 1kg each were placed in a bucket that was chained to a wooden board. A pair of widgets was added until the board broke. 54 widgets were added when the board was broken. Calculations revealed that it took 530.15N of force and 3.71105 J of energy to break the board. Then, the mass of the hand was measured using displacement of water and a Newton scale. The measurements were averaged together, resulting in a value of 0.500kg. The speed of the hand was then measured using neon lights and a photogate timer. The measurements were averaged together, resulting in a value of 11.06 m/s. Calculations revealed that the hand exerted 4350N of force and 30.6J of energy. It was more than enough to break the board. Lastly, wooden boards were placed on two level edges and pummeled by fists. Key Words: Impulse – the amount of force applied over a time interval. Momentum – the mass multiplied by the speed. Widgets – pre-weighted metal used to measure the force needed to break a board. Inertia – the resistance an object has to a change in its state of motion. Kinetic Energy – the total amount of work done on an object during the process of going to rest. Sag – the distance to which the board bends after weight is added to it Introduction: In physics, force can be described as “ an influence on a body or system, producing or tending to produce a change in movement or in shape or other effects”
(Dictionary.com). In this experiment, the goal was to figure out whether or not the hand could produce enough force and had enough energy to break a wooden board. To determine the amount of force necessary to break the board, the equation Force = (average mass of widget)*(acceleration due to gravity)*(number of widgets used to break the board) was used. The average mass of the widgets was found to be 1.0018kg and 9.8m/s 2 was used as the acceleration due to gravity. The amount of energy needed to break the board was calculated to be 3.71105J. The force of the hand as it hit the board was found by using the impulse equation FΔt = mΔv, where m was the mass of the hand and Δv was the speed of the hand. Δt was the stopping time of the hand. Because the board bends to a certain distance before breaking, Δt was found by using the equation

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## This note was uploaded on 09/19/2011 for the course 1 101 taught by Professor Larrydavid during the Spring '11 term at South Carolina.

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Karate Lab - Relating the Force and Energy of a Closed Fist...

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