Motion Along A Straight Line

1. Motion Along A Straight Line Position Displacement Speed Velocity Acceleration Rules for Derivatives Free Fall Acceleration Rules for Integration pps by C Gliniewicz

2. Motion is a change in position. It needs no reference to time, but implies time. • Kinematics is the study of motion. At first we study motion along one axis considering a point particle to be moving. • Position is the location relative to some reference point which we might call the origin. • Displacement is the straight line change in position from one point to another. • Direction is designated by plus and minus signs along a straight line. • The value of the displacement is the magnitude and is the absolute value of the displacement. • The displacement is a vector and has a magnitude and direction associated with it. • Position can be represented on a graph of position vs. time. • Average velocity is the ratio of the displacement (change in position) to the time interval required for the displacement. • Average speed is independent of the direction. It is the ratio of the total distance traveled to the total time required. This would be similar to the odometer reading of an auto divided by the time of the trip. pps by C Gliniewicz

3. Instantaneous velocity is commonly thought of as how fast a particle is moving at a particular time. • It is actually a limiting quantity. • The last quantity is the derivative of the position with respect to time. • Instantaneous speed is the same as the instantaneous velocity but without any reference to the direction. • Instantaneous acceleration is the change in velocity with respect to time. • An acceleration is negative when the speed is decreasing. The acceleration is positive when the speed is increasing. pps by C Gliniewicz

4. Rules for finding derivatives pps by C Gliniewicz

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6. Free Fall Acceleration is the acceleration due to gravity. • By convention, up is positive and down is negative. • Down means toward the center of the earth and is a different direction at different locations on the earth’s surface. • One uses the same kinematics equations except in place of the acceleration, a, one uses the acceleration, g. pps by C Gliniewicz

7. Rules for Integration Integration is just differentiation in reverse. pps by C Gliniewicz

8. To prepare for the AP Physics exam, one should do the following when solving problems. • Write the given information so it is easy to read. • Write the symbols for the requested information. • Write the equations which you think you need to use. • Write out the equation with the given information entered into the equation. • Sometimes two different equations for the same quantity can be set equal to cancel out information which is not given in the problem. • Solve for the necessary data. • Circle the answer with the proper units. • Check to see if the magnitude seems appropriate to the question asked. Ask yourself if the quantity seems much too large or much too small for the problem. pps by C Gliniewicz