Impulse In Rugby What Is Impulse? Brian Lima (97kg) hits Derick Hougaard (85kg) Breakdown Bibliography ............................. By: Luke Gerweck Impulse is defined as a change in momentum The Impulse Equation is F t= p= mv1 - mv0 The Side F t, is the time a the force acts upon the object p, is the change in momentum between times mv1 -mv0, is the mass and final velocity MINUS the mass and the initial velocity http://en.wikipedia.org/wiki/Impulse_(physics) http://en.wikipedia.org/wiki/Brian_Lima http://en.wikipedia.org/wiki/Derick_Hougaard So as you saw, Brian Lima was able to stop Derick Hougaard in his tracks. Lets take a look at the physics behind this. Brian Lima, was able to get a running start, from 8 meters out, allowing him to reach a speed of roughly 10m/s. Derick Hougaard was moving at only about 4m/s, due to the fact that he had to jump to secure the ball. The t of this contact is .57 seconds Plugged in to the Formula Using the data that was recovered from the video and stat books, we get a formula that looks something like this. Brian Lima's momentum is -970, while Derick Hougaard's momentum is 340. 97x-10= -970, 85x4=340. Due to the fact that they both moved backwards, this is an Inelastic Collision. They stick together and move in the same direction. The Collision Formula looks like this:

(97kg)(-10m/s) + (85kg)(4m/s) = 182 vf

-3.46 = vf Now on to Impulse The Impulse Equation is I = mvf - mvi

(97)(-3.46) - (97)(-10) = 634.2 kgm/s Using I= F T, I know that average force is

I/ T 634.2 kgm/s | .57 = 1112.6 N 1112.6 N is the force behind this tackle. Wowza! This is the same magnitude for both players. This is due to Newtons Third Law. Rugby Penalty Kick This kick, taken by Leigh Halfpenny of Wales, traveled 52 meters horizontally in 3.98 seconds. A Penalty kick is taken from a tee, at distances ranging from 22, to 65 meters from the goal posts. The Kick The Details Behind the Kick The Ball, weighs .46 Kg The Ball travels 52 meters, in 3.98 seconds, The time of impact is .07 seconds The Science Behind the Kick V= Vi + AT

At the top of the arc, the VY is 0

And the time will be half of the total time. 0= VY + (-9.8) T/2

VY= 9.8 * 3.98/2 VY= 4.9 (3.98) VY= 19.502 M/S The Science Behind the Horizontal Vx = D/T Vx = 52 / 3.98 Vx = 13.07 M/S Total Velocity A^2 + B^2 = C^2 19.502^2 + 13.07^2 = C^2

551.2 = C^2

23.48 = C C is Velocity in M/S Impulse of the Kick I= Mvf - Mvi I = .46(23.48) - .46(0) I = 10.8 KgM/S F= I/ t F= 10.8/ .07 F= 154.3 N http://www.worldacademicunion.com/journal/SSCI/SSCIvol06no02paper03.pdf http://entertainment.howstuffworks.com/physics-of-football4.htm http://www.unc.edu/~ahaftman/PHYS%20EC/PHYS%20EC/Physics%20of%20a%20Rugby%20Tackle.html

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# Rugby Impulse

The Impulses and Momentum taken from the World's Greatest Game

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