Linear motion . (a) define displacement, speed, velocity and acceleration (b) use graphical methods to represent displacement, speed, velocity and acceleration (c) find displacement from the area under a velocity-time graph (d) use the slope of a displacement-time graph to find the velocity (e) use the slope of a velocity-time graph to find the acceleration (k) describe and explain motion due to a uniform velocity in one direction and a uniform acceleration in a perpendicular direction.

Displacement Is a measured distance in a given direction It tells us not only the distance of the object from a particular reference point but also the direction from that reference point It is a vector quantity In many situations it is measured from the origin of a Cartesian co-ordinate system

Speed Is the rate of change of distance Or the distance covered per unit time Speed is the total distance (d) covered in total time (t) Speed (s) = total distance (d) / total time (t)

Velocity Is the rate of change of displacement Is a measured speed in a given direction It tells us not only the speed of the object but also the direction It is a vector quantity

Instantaneous and average values The average value of speed, velocity and acceleration are the average over a time period. They are calculated by the equations s=(d2-d1)/t, (s2-s1)/t and (v-u)/t The instantaneous values are for an instant in time (vanishingly small values of t) They can be found from the gradient at a certain point on a d (s,v) vs t graph

Acceleration Is the rate of change of velocity in a given direction a = Δv / Δ t (where Δ v = v – u) It is a vector quantity If the acceleration of an object is positive then its rate of change of velocity to be positive and it could mean that its speed is increasing Do not think of acceleration as a ´slowing down´or a ´getting faster´. Avoid speaking of faster acceleration or slower acceleration

Drawing graphs Students should be able to sketch and label d-t (s- t), v-t and a-t graphs for various situations. They should also be able to write descriptions of the motions represented by such graphs. Thanks to mhtml:http://physics.greengates.edu.mx/IB%20PowerPoints/02.%20Mechanics/2.1%20Kinematics.mht!2.1Kinematics_files/frame.htm

Projectile motion