0517 Physics - Motion, Acceleration and Forces Eric...

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Unformatted text preview: Motion, Acceleration and Forces Eric Richardson, M.D. Cheongshim International Academy S1 Describing Motion Motion How would you describe the motion of How people and things around you? people It’s an age old problem Describing motion Aristotle’s notions of Aristotle’s motions (384-322) motions Natural motion Forced motion Voluntary All motion is in a All straight line straight Except heavenly Except motion motion Aristotelian motion: http://library.thinkquest.org/11924/aristotle.html Describing motion Aristotle’s notions of motions (384-322) Natural motion Forced motion Voluntary All motion is in a straight line Except heavenly motion Aristotelian motion: Describing motion Describing motion Galileo Progress of practical Progress experience: experience: Art: More careful Art: observation and perspective perspective Use of cannons in Use warfare warfare Why? Describing motion Galileo Developed the concept of Developed inertia inertia Showed that a ball moving Showed as in this experiment follows a curved motion follows Aristotelian motion: http://library.thinkquest.org/11924/aristotle.html Galileo Known as the father of Known astronomy, but also like the father of science father Utilized scientific method: Careful observation Careful notekeeping Careful and measurement and Making hypotheses Predicting and repeated Predicting testing testing Verifiable results Describing motion Isaac Newton Careful observation and records keeping Developed concept of inertia into the First Developed Law of motion “An object at rest tends to stay at rest An and an object in motion tends to stay in motion unless acted on by an outside force.” force.” Famous mathematical formula of the 2nd Famous law gave changes in motion a firm mathematical basis. mathematical F=ma Aristotelian motion: http://library.thinkquest.org/11924/aristotle.html S1 Describing Motion Motion How would you describe the motion of How people and things around you? people 1. Motion is a change in position • So you don’t need to see it move, So if the position changes in relation to other things around it. to S1 Describing Motion Motion How would you describe the motion of How people and things around you? people 1. Motion is a change in position 2. Position depends on a reference frame. • So, how you describe where something So, is depends on what things you define as being near it. as S1 Describing Motion • Motion How would you describe the motion of How people and things around you? people 1. Motion is a change in position 2. Position depends on a reference frame. 3. Motion is relative. So, without these elements in our description, it So, is difficult to describe motion. is S1 Describing Motion Distance vs Displacement The total distance travelled The is sometimes very different from how far you end up from the starting point. from The distance from the The original starting point is the displacement the Displacement includes Displacement measurement of length and has a direction, therefore it’s a…? it’s S1 Describing Motion SPEED “I feel the need… the need… for SPEED!” Tom Cruise in Top Gun QuickTimeª and a TIFF (LZW) decompressor are needed to see this picture. S1 Describing Motion Speed The distance an object The travels per unit time travels Instantaneous speed What you would see on What your speedometer in the car car S1 Describing Motion Average speed Describes how fast the Describes object moved over the entire distance it traveled. entire It is equal to the total It distance traveled divided by the total time it took to get there. get S1 Describing Motion d v= t S1 Describing Motion d v= t Problem 1: An elevator travels a distance of 220 m from the first floor to the 60th floor in 27.5 seconds. What is the elevator’s average speed? Problem 2: A motorcyclist travels with an average speed of 20 km/h. If the cyclist is going to a friend’s house 5 km away, how long does it take the cyclist to make the trip? S1 Describing Motion Velocity Speed and Speed Direction VECTOR Direction Both escalators are Both going the same speed but the direction is different different S1 Describing Motion Velocity Speed and Speed Direction VECTOR VECTOR Earth goes Earth around the sun in a nearly constant speed speed What about the What velocity? velocity? ...
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This note was uploaded on 09/26/2011 for the course AS as taught by Professor Fds during the Spring '11 term at Columbia School of Broadcasting.

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