Displacement Key Point: (Std 8-5.1) Use measurement and time-distance graphs to represent the motion of an object in terms of position, direction, or speed.

Motion a change in position with respect to a reference starting point usually described/determined by: – Position – Direction

Position the location of an object An object changes position if it moves relative to a fixed reference point. displacement: the distance and direction of an object’s change in position from the starting point.

Direction The line or path along which something is moving, pointing, or aiming. Measured using a reference point with terms such as: up, down, left, right, forward, backward, toward, away from, north, south, east, or west.

For example… Given this data table, determine the change in the object’s position based on its final position, distance, and direction from the starting point. SegmentDistance (m) Direction X10East Y7North Z10West

For example… Given this data table, determine the change in the object’s position based on its final position, distance, and direction from the starting point. SegmentDistance (m) Direction X10East Y7North Z10West X

For example… Given this data table, determine the change in the object’s position based on its final position, distance, and direction from the starting point. SegmentDistance (m) Direction X10East Y7North Z10West X Y

For example… Given this data table, determine the change in the object’s position based on its final position, distance, and direction from the starting point. SegmentDistance (m) Direction X10East Y7North Z10West X Z Y

Distance Travelled = __________m Displacement = ______________________ SegmentDistance (m) Direction X10East Y7North Z10West X Z Y

Distance Travelled = 27 m Displacement = 7m north of the starting point SegmentDistance (m) Direction X10East Y7North Z10West X Z Y

Graphing Changes in Motion

Distance-Time Graph A graph that can be used to represent how both speed and distance change with time. x-axis = Time y-axis = Distance Always label axis. Keep numbering consistent. Include units.

Time (s) Distance (m)

Constant Motion Constant motion is represented in a graph by a straight line.

There are 3 segments in this graph where motion is constant: – between minutes 0 and 4, 4 and 6, and 6 and 10. Even though between these points motion is constant, the overall motion changes.

Change in Motion You can tell when motion changes because the line is not straight. Can be seen as: a change in the straight line, or a curved line. (not constant between any two points)

Change in Direction On a motion graph, you can tell when the object reverses direction because the distance from the starting point becomes less.

Based on what you now know about distance-time graphs, describe what you believe is happening to the speed in the 4 segments of this graph.

Speed Key Point (Std 8-5.2): Use the formula for average speed to solve real world problems.

Speed A measure of how fast something moves a particular distance over a given time. – It does NOT necessarily mean that it’s fast. Speed is the rate of change of the position of the object, or how far something will move in a given period of time.

Acceleration Acceleration is the increase or decrease in speed. When motion is constantly changing. Is a curved distance- time graph. (not constant between any two points) This graph shows increasing speed because the curve goes upward.

Slope The steeper the slope on a distance-time graph, the greater the speed. Zero slope (flat line) means motion has stopped. (time is passing, but there is no increase/decrease in distance)

Calculating Speed While the speed of the object may vary during the total time it is moving, the average speed is the result of the total distance divided by the total time taken. Formula: speed = distance time v = d t d t v

1.If you traveled 125 meters in 20 seconds, what was your speed? speed = distance time v = 125 meters 20 seconds V = 6.25 m/s d tv

2.How far would you travel if you were going 88 mi/hr for 3.2 hours? distance = speed x time d = 88 mi/hr x 3.2 hrs d = mi d tv

3.If you traveled at 60 m/s for a distance of 320 meters, how long would it take you to get there? time = distance speed t = 320 meters 60 m/s t = 5.3 s d tv

Copy this table and complete the blanks. Show your work in the area below the chart. TimeDistanceSpeed 1)15 s325 m 2)2.4 mi3.2 mi/hr 3)1.5 hr91.2 in 4)54 ft1.5 ft/min 5)35 s6.35 m/s

Answers TimeDistanceSpeed 1)15 s325 m21.7 m/sec 2)0.75 hr2.4 mi3.2 mi/hr 3)1.5 hr91.2 in60.8 in/hr 4)36 min54 ft1.5 ft/min 5)35 s m6.35 m/sec