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PHYS 121 Lecture Notes

# PHYS 121 Lecture Notes - Lecture Notes Sunday 1:20 PM...

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GENERAL PHYSICS I - MECHANICS Day Time Location M W F 1130a-1220p STRO AUD Pasted from < http://www.phys.cwru.edu/courses/p121/ > Lecture Notes Sunday, August 26, 2007 1:20 PM PHYS 121 Page 1

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We will start by simplifying kinematics to one-dimensional velocity . a. Average velocity is given by b. Instantaneous velocity is given by and is graphically equivalent to the slope on a graph of position versus time. c. There is a constant velocity if and only if the graph of position versus time is linear. When this occurs, position as a function of time is given by d. The investigation of position as a function of time is known as kinematics . 1. Forces are interactions between two bodies that cause acceleration , the rate of change of velocity. 2. If there is no acceleration, there is no net force, and conversely, if there is no net force, there is no acceleration. With respect to an inertial frame , a body accelerates only when a physical force is applied, and (following Newton's first law of motion), in the absence of a net force, a body at rest will remain at rest and a body in motion will continue to move uniformly i.e. in a straight line and at constant speed. a. If there is an acceleration, then the net force is not zero and is proportional to that acceleration at each instant in time. The proportionality constant measures how hard it is to move the given body, and it makes sense that this constant is the mass, M . b. If the force on body 1 is due to body 2, then body 2 feels an equal and opposite force due to body 1. c. Newton's laws of motion 3. x v t dx v dt 0 ( ) x t x vt 0 0 total net individual F F F a net F Ma on 1 by 2 on 2 by 1 F F   Lecture 1 Monday, August 27, 2007 11:30 AM PHYS 121 Page 2
Average velocity is given by 1. Average speed is given by and is always positive. 2. Instantaneous velocity is given by 3. Average acceleration is given by 4. Instantaneous acceleration is given by 5. Because of Newton's second law, a larger M causes a smaller acceleration for a given force, and vice versa. Therefore, the same force accelerates different masses differently. 6. Whenever there is a constant acceleration , Also, when acceleration is constant, 7. Jerk is the time derivative of acceleration, and when there is constant jerk , 8. 2 1 2 1 displacement during a time interval time interval x x v t t total displacement gone regardless of direction time interval av speed 2 1 2 1 1 1 0 2 1 lim lim ( ) ( ) t t t x x x dx v t v t t t t dt   2 1 2 1 v v a t t 2 1 2 2 1 1 1 1 2 0 2 1 lim lim ( ) ( ) ( ) t t t v v v dv d x a t t a t t t t dt dt   net F Ma 2 0 0 0 0 2 0 0 0 1 and 2 1 2 dv dx a v a t C v a t C x a t Ct D dt dt x a t v t x 0 0 0 2 0 0 0 3 2 0 0 0 0 1 2 1 1 6 2 da j dt dv a j t a dt dx v j t a t v dt x j t a t v t x 2 2 0 0 0 2 ( ) v v a x x Lecture 2

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PHYS 121 Lecture Notes - Lecture Notes Sunday 1:20 PM...

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