Ch.3 Study Guide

A Daniel Sims study guide

cturing motion

1.1 Motion diagrams 1.1.1 a motion diagram is a powerful tool for studying motion 1.1.1.1 it is consecutive frames were the background is the same 1.1.2 when the motionless objects in the background do not change position the object is at rest. 1.1.2.1 If the change in position between each frame gets bigger the object is moving faster if it's getting shorter it's slowing down. 1.1.2.2 If the distance between each image in each frame is the same the the object is moving at a constant speed. 1.1.3 The 4 concepts of the study of motion 1.1.3.1 at rest 1.1.3.2 speeding up 1.1.3.3 slowing down 1.1.3.4 constant speed 1.1.3.4.1 each of these are called operational definition 1.2 The particle model 1.2.1 keeping track of an object is easier if one disregarded things like spinning wheel, arms, legs, and bobble head dolls, on concentrated on a single point on the object. 1.2.1.1 This type of model is called a particle model 1.2.2 /////CRITICLE-WARNING\\\\\\ in order to use the particle one MUST make sure the size of the object is less then the distance it moves Where and when? 2.1 Coordinate system 2.2 Placing a clock and a meter stick in the path of a camera helps one deter man the distance and travel at each time interval. 2.2.1 By doing this the experiment crew defines the coordinate system. 2.2.1.1 This tell you the zero point of the variable you are studying and the direction those variables increase. 2.2.1.1.1 The point at which the variables have the value zero is called the origin 2.2.2 in a motion diagram the origin would be zero on the measuring device. 2.2.3 The measuring device should be in a straight line 2.2.3.1 how ever it does not matter if the tape if going left or right relative to the camera. 2.2.4 A position vector is used to find the distance traveled relative to the origin. 2.2.4.1 The arrow would go to the dot on a particle model. 2.2.4.2 The length of the arrow is perpotional to the distance of the object from the origin and the points from the location of the object at a particular time. 2.2.4.3 Negative positions are possible 2.3 Vectors and scalars 2.3.1 a quantity that tells you the magnitude of something is called a scalar quantity. 2.3.2 The distance between two cities is a scalar quantity 2.3.2.1 When represented by an arrow it is a vector quantity 2.3.2.2 Scalar quantities are represented by letter while vectors have a letter and a line over it. 2.4 Time intervals and displacement

2.4.1 Displacement is the distance and direction between two points 2.4.2 to find the time of movement subtract the end time from the start time or T0 – T1 2.4.2.1 This time is called time interval 2.4.2.1.1 a common Symbol for this is delta T 2.4.2.2 The size of this vector is called the distance Velocity and acceleration 3.1 delta T would be smaller for something going faster then something going slower 3.1.1 Average Velocity 3.1.1.1 Formula is Average velocity = delta D/Delta T = D1 – D0/ T1 – T0 3.1.1.2 Average speed is the ratio of the total distance traveled to the time interval 3.1.2 Instantaneous velocity 3.1.2.1 All that can be determined from a motion diagram is an average interval. 3.1.2.2 The speed and direction of an object at a particular instant in time is instantaneous velocity. 3.1.3 Average velocity motion diagrams 3.1.3.1 the formula is d1 = d0 +VdeltaT 3.1.3.1.1 in words over the time interval delta t the average velocity of a moving abject results in a change in position = to velocity Delta t 3.1.3.1.2 acceleration is change in velocity to the time interval over which it occurs. Or Delta V/Delta T = Acceleration 3.1.3.1.3 The formula for avg acceleration is 3.1.3.1.4 a =

deltaV deltaT

3.1.3.1.4.1 Use meters per seconds per second as the unit 3.1.4 Using motion diagrams to obtain average acceleration 3.1.4.1 in a motion diagram the avg. acceleration vector is proportional to the change in the avg. velocity. 3.1.4.2 When there is no change in avg velocity avg acceleration is zero 3.1.4.3 when avg velocity goes up avg acceleration goes up too 3.1.4.4 when avg velocity goes down avg acceleration goes down 3.1.5 Problem solving strategy: sketch the problem 3.1.5.1 sketch the problem 3.1.5.1.1 sketch the situation 3.1.5.1.2 add a coordinate system to the problem 3.1.5.1.3 give symbols to the known variables 3.1.5.1.4 give symbols to the unknown variables 3.1.5.1.5 now you have a pictorial model, now make a physical model 3.1.5.2 calculate your answer 3.1.5.3 Check your answer 3.1.5.3.1 ask your self these question 3.1.5.3.1.1 did i answer the question 3.1.5.3.1.2 is the answer reasonable