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Unformatted text preview: 1 Kinematics is the description of motion. Kinematics is concerned with &quot;What is happening?&quot; or &quot;How is this moving? KINEMATICS: The mathematics of motion Chapter 2 [s] = m = position [v] = m/s = velocity [a] = m/s 2 = acceleration () s a v v t a v v t a t v s s s is fs s is fs s is i f + = + = + + = 2 2 1 2 2 2 2 2 1 t a t v x x x xi i + + = How many variables???? x v x x a v v t v t a v v t x t a t v x x i x xi x x xi x x xi i + = + = + + = ) ( 2 2 1 2 2 2 b mx y + = Each kinematics equation has ________ variables. ________ ________ ________ Uniform Motion Straight line motion in which equal displacements occur during an successive equal time interval is uniform motion . For one dimensional motion t s v avg = r r t y v OR t x v avg avg = = r r Motion is uniform if and only if its ___________ is constant and unchanging. Distance and Displacement Displacement is the difference between the final position, x, and the initial position, x i . m 100 m 50- m 150 x- x x i = = = m 150 x = m 100 x i = i x x x = ________ ________ 2 A displacement to the left will be a negative displacement. Distance is the absolute value of the displacement. Distance is always _______ and tells how far something is from something else but does not tell us whether it is to the right or to the left. m 150 x i = m 50 x = m 100- m 150- m 50 x- x x i = = = Distance and Displacement _______ Velocity Velocity has units of displacement divided by time. m/s, km/h mi/hr and is a vector (showing magnitude and direction) If a motorcycle travels 20 km in 2 h, then its average velocity is If a ball rolls from a position at 10m to a position of 0m in 2.0 s, then its average velocity is i f i f x t t x x t x v = = h km 10 h 2 km 20 t x v x = = = s m 5 s 2 m 10 m t t x x v i f i f x = = = 20 km ________ _______________ Speed If a ball rolls from a position at 10m to a position of 0m in 2.0 s, what is its average speed ? Average speed = Speed is not a vector, only a ________! s m 5 s m 5 v = = Velocity: is positive if an object is moving to the right and it is negative if an object is moving to the left. Speed: tells how fast an object is moving without saying anything about its direction. Speed is * always positive * absolute value of the velocity __ Velocity Average velocity tells nothing about what happens between x i and x . Graphically we can see this..Graphically we can see this....
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- Spring '08