Chapter 3 Notes

# Chapter 3 Notes - Sprinter Biomechanics Forces Newton Laws...

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1 PHYS 1L03, Winter 2009, McMaster University, R.Nejat Sprinter Biomechanics Forces, Newton Laws Concepts: Force Newton’s Laws Free body diagram Equilibrium Chapter: 3, 4 Pages: 40-70, 103-105 PHYS 1L03, Winter 2009, McMaster University, R.Nejat Biomechanics • Sprinters require maximum acceleration. PHYS 1L03, Winter 2009, McMaster University, R.Nejat Biomechanics • How does sprinter acquire acceleration? • Does the push exerted by Sprinter on the starting block directly give him acceleration? • How does sprinter exert the push (a force)? • What is force and what does a force do? PHYS 1L03, Winter 2009, McMaster University, R.Nejat Biomechanics • How does sprinter exert a force? • How do we exert forces? • What is force and what does a force do? Questions: PHYS 1L03, Winter 2009, McMaster University, R.Nejat •Fo rce is : –a push or a pull that one object exerts on another. –a vector, having both magnitude and direction. • When you apply a force, , on an object, at the same time the object , on you in the same magnitude but opposite direction. Force F r F r PHYS 1L03, Winter 2009, McMaster University, R.Nejat Force on an object A mule and a cart: – A mule applies a force on a cart, and the cart applies a force with the same magnitude but in opposite direction on the mule.

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2 PHYS 1L03, Winter 2009, McMaster University, R.Nejat What is going on in this picture? Force PHYS 1L03, Winter 2009, McMaster University, R.Nejat • When you kick a ball, your foot exerts a force on the ball while the two are in contact 1 , changing the velocity 2 (the speed and/or the direction) of the ball. 1 :-- Force is an interaction between two objects . 2 :-- Force (external) changes the velocity, causes acceleration , of the object. Force: PHYS 1L03, Winter 2009, McMaster University, R.Nejat Brief Review on adding vectors • If you do not remember how to add vectors in component form, you should watch the tutorial video on vectors posted on ELM • DO NOT SKIP THIS STEP OR YOU WILL BE LOST FOR THE REST OF THE TERM! PHYS 1L03, Winter 2009, McMaster University, R.Nejat Brief Review on adding vectors • We can always break any 2D vector up into components along two perpendicular axes, such as x and y: θ PHYS 1L03, Winter 2009, McMaster University, R.Nejat θ Brief Review on adding vectors y x A A A r r r + = θ cos A A x = sin A A y = 2 2 2 x x A A A + = 2 2 x x A A A + = x y A A = tan ( ) y x A A A r r r , = () y x A A A , = r , A A = r PHYS 1L03, Winter 2009, McMaster University, R.Nejat Review: Adding two vectors: • Find the resultant of two vectors F 1 and F 2 , shown below = iy y F R F 1 F 2 R = ix x F R 2 1 F F R r r r + = A simple way to find the resultant of two vectors is finding the components of it. 1. Find the x and y components of each vector. 2. x-component of resultant is the summation (algebraically) of x- components of vectors.
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## This note was uploaded on 02/14/2011 for the course PHYS 1L03 taught by Professor Hughes during the Spring '11 term at McMaster University.

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Chapter 3 Notes - Sprinter Biomechanics Forces Newton Laws...

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