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lecture3 - Ch. 2 Kinematics in 1-D Mechanics Kinematics...

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Ch. 2 – Kinematics in 1-D Mechanics Kinematics Dynamics Concepts needed to describe motion w/o forces Deals with the effects that forces have on motion Chs. 2 and 3 Ch. 4 ur goal is to describe the motion of some object. Our goal is to describe the motion of some object. To do this, we must be able to specify its location in space at all times! In other words, what is the position of some object at time t ? Define Displacement : A vector which points from an object’s initial position to its final position.
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In this chapter, we will only consider 1 dimensional motion. Let’s look at the following example : t time a jogger’s position relative to some fixed origin is At some later At time t = t o , a jogger s position relative to some fixed origin is x o . At some later time, t = t f , her position relative to the origin is x f . What is her displacement during this time interval? t = t o t = t f x origin x o x f Δ x Her displacement, x , is the difference in her initial and final positions. Displacement = x = x f x o x is pronounced “delta x”, or “change in x”. Units? he SI unit of displacement is the meter (m). The SI unit of displacement is the meter (m). In 1-D we can also talk about scalar displacement , which is just a number. It can be either positive or negative. For example, in the above problem, if x o = 10 m and x f = 30 m, then her scalar displacement would be positive 20 m.
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2.2 Speed and Velocity One of the most fundamental description of an object’s motion is its speed ow fast its moving how fast its moving. If I run 30 m in 10 s, then my average speed is = 30 m 10 s = Distance Time = 3 m/s Units? The SI unit for speed is m/s . *Important concept We are talking about constant speed , which means we will cover the same distance in the same time interval. Time Elapsed Distance Speed ave. = Speed tells us how fast an object is moving, but it doesn’t say anything about its direction of motion. peed is a calar ! Speed is a Scalar !!! Now let’s talk about average velocity .
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Velocity is a vector ! It tells you both the speed and the direction the object is moving! Distance peed nt Displaceme elocity Time Elapsed Speed ave. = Time
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This note was uploaded on 08/04/2009 for the course PHYS 2001 taught by Professor Sprunger during the Fall '08 term at LSU.

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lecture3 - Ch. 2 Kinematics in 1-D Mechanics Kinematics...

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