Chapter 9 Motion 8 th Grade Science

Motion An object is in _________ if its distance from another object is changing. _____________ - a place or object used to determine if its distance from another object is changing - _____________ - objects that are not moving. ___________ - whether or not an object is in motion depends on the reference point. motion Reference Point Stationary objects Relative Motion

Measuring Distance ______________________ - system of measurement that scientists all over the world use to communicate _______ measure the distance an object moves ______ measures length ______ - the SI unit of length One meter is a little longer than a _____. International System of Units (SI) SI Units Distance meter yard

SI Units ___________ - one hundredth of a meter – there is one hundred centimeters in a meter ____________ - one thousandth of a meter – there are one thousand millimeters in one meter __________ - 1,000 meters Centimeter (cm) Millimeter (mm) Kilometer (km)

Speed and Velocity ______ - the distance an object travels per unit of time. If you know the ________ an object travels in a certain amount of time, you can calculate the _______ of the object. Speed is a type of ____ _____ - the amount of something that occurs or changes in one unit of time Speed distance speed rate

Calculating Speed

Speed If you measure _________in _________ and _______ in _________, then ________ would be expressed in _________________ If you measure _________ in ________ and _______ in _______, then _____ would be expressed in ___________________ distancemeters timesecondsspeed Meters per second or m/s distancekilometers time hoursSpeed Kilometers per hour or km/h

Average / Instantaneous Speed _____________ is calculated when the speed of the moving object is not constant Average speed is calculated by dividing the _______________ by the _____________ _______________ - the rate at which an object is moving in a given instant in time _______ - speed in a given direction When you know speed and direction of an objects motion then you know the velocity of the object Average speed Total distance traveled Total time Instantaneous speed velocity

Graphing Motion __________ - show motion by plotting _______ versus ____. _____ - shown on the ________ or _________ ________ - shown on the _______ or _________ A ______ on the line represents the ________ an object has traveled at a particular time Line graph distancetime Timehorizontal X - axis Distancevertical Y - axis point distance

Slope ______ - the steepness of a line on the graph Slope tells you how ___ one variable changes in ______ to another variable RATE OF CHANGE ______ = the rate that distance changes in relation to time, therefore the _______ of a distance versus time graph represents _______. slope fast relation speed slope speed

Calculating Speed _____ - vertical difference between any two points on a line _____ - horizontal difference between the same two points ______________ - calculate the slope of a line by dividing _______ by the _____ Rise and run rise runrise run

Acceleration ___________ - the rate at which velocity changes A change in _______ can either be a change in _____ or _________ or ______ Acceleration can either be: – ________________ – __________________ acceleration velocity speeddirectionboth Increasing speed Decreasing speed Or changing directions

Calculating Acceleration Acceleration of an object moving in a straight line - _____________________________ Acceleration = ___________________ If speed is measured in meters per second then acceleration is measured in _________ _____________ - m/s ² Calculate the change in speed per unit of time Final speed – initial speed Time Meters per Second per second

Acceleration Continued If speed is measured in kilometers per hour, then acceleration will be measured in ___________________ - km/h² Page 323 – Math Practice – 1 and 2 Kilometers per hour per hour

Graphing Acceleration ________________ - acceleration on this graph is represented by ____________ __________________ - acceleration is noted by an increase in slope Section 3 Assessment – page 325 – 1 through 5 Speed versus Time Graph Rise / Run – slope Distance versus Time Graph