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Lec05_Sum_f

# Lec05_Sum_f - Summary Lecture 5 A projectile is any object...

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1 Lecture 5 Dynamics Force Newton’s Laws of Motion Physics 111, Summer 2011, June 20, Lecture 5 Summary An object has one or two components of the initial velocity: along x (horizontal) direction and along y (vertical) direction. 2 A projectile is any object that is given an initial velocity and then follows a path determined by the horizontal and vertical motion (air resistance is important by can be ignored). Projectile motion is simultaneous motion in horizontal and vertical directions. An object has one non-zero component of acceleration: along x (horizontal) direction: along y (vertical) direction. Equations for projectile motion, vertical component: Equation for projectile motion, horizontal component: 0 x v 0 y v 0 x a g a y gt v v y y 0 2 2 0 gt t v y y const v v x x 0 t v x x 0 Physics 111, Summer 2011, June 20, Lecture 5 Dynamics Kinematics: explains how objects move. Dynamics: explains how objects motion depends on forces acting on them. We use: distance, time, speed, velocity, and acceleration. We use: force , distance, time, speed, velocity, and acceleration. Force is the most important parameter describing dynamics. 3 An object changes its velocity, i.e. accelerates, if: - it moves faster, or - it moves slower. Why? Because some force is applied, Physics 111, Summer 2011, June 20, Lecture 5 Force is a quantitative description of the interaction between two physical bodies, such as an object and its environment. Force is any influence that causes a free body to undergo a change in speed, a change in direction, or a change in shape. What is Force? 4 Physics 111, Summer 2011, June 20, Lecture 5 The concept of force was originally defined by Isaac Newton in his three laws of motion. He explained gravity as an attractive force between bodies that possessed mass. Definition The concept of force

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