 # Motion Chapter 10 Section 1 Measuring Motion PAGES 316-324 25.

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Motion Chapter 10 Section 1 Measuring Motion PAGES 316-324 25

Objectives Explain the relationship between motion and a frame of reference. Relate speed to distance and time Distinguish between speed and velocity Solve problems related to time, distance, displacement, speed and velocity 25

Observing Motion Motion is described in relation to another object that stays in place– a stationary object The stationary object is a reference point sometime is called a reference frame or frame of reference 26

Distance Distance measures the path taken A B 27

Displacement-the change in position of an object A straight line between the start and finish Difference is straightness and direction Toward B A B 27

Distance vs Displacement

Project Design a demonstration that illustrates the difference between distance and displacement You may use a toy car, airplane, rat, use your imagination Be ready to present next class!

Speed Speed describes how fast something moves Speed the distance traveled divided by the time interval S = d/t for example 5m/s Meters / second the slash is read per 28

Time Distance Graph Slope of the line is the object’s speed 28 Dependent variable independent variable

Constant speed The speed does not change Most objects do not move with constant speed 29

Instantaneous Speed The speed at a given point in time NASCAR 173.45 MPH The car’s speed at that instant A car’s speedometer 29

Speed Speed-- how fast something is going Speed is a scalar quantity. Scalar tells the amount of something 30

Formula— Time is measured in Seconds or hours Distance is measured in cm, km, or m 50 km—d 2 hrs—t How fast—speed 50km/2hr=25km/hr s=d/t 30

Velocity Velocity is speed and direction Velocity is a vector quantity. A vector shows speed and direction. Vectors are arrows that show direction.

Velocity Velocity is speed and direction Velocity is a vector quantity. A vector shows speed and direction. Vectors are arrows that show direction.

Does your velocity change? Yes... Because the direction changed and velocity includes both speed and direction

Draw an arrow over the number indicating speed 50m/s

Velocity Vectors Velocity uses the same units but can include a vector arrow that indicates direction

Velocity Vectors 80 120 100 With the wind Same--Add Against the wind opposite--subtract 100 20

Worksheet Velocity Note the longer the line the faster you are going The shorter the slower

Using vectors

Parallelogram rule: when given two vectors draw parallel lines. The diagonal of the parallelogram is the resultant

Velocity Speed and direction Velocity is a vector quantity. Escaped lion You need to know his speed and direction!!!! 31

Velocity Vectors A vector shows the direction and magnitude (speed) of an object 31

Draw an arrow over the number indicating direction and approximate speed 50m/s 31 Velocity uses the same units as speed but can include a vector arrow that indicates direction

Using vectors Parallelogram rule: when given two vectors draw parallel lines. The diagonal of the parallelogram is the resultant 32

Velocity Vectors 80 120 100 With the wind Same--Add Against the wind opposite--subtract 100 20 33

Freefall -- an object falling free of all restraint 34

V=at Velocity = acceleration times the time a– acceleration t – time Acceleration due to gravity is 9.8m/s 2 34

How fast? v=at 0s1s2s3s4s5s6s7s8s 34

Distance of Fall 012345678 D=1/2at 2 35

Freefall speedometer—shows how fast odometer—shows how far Two equations v=at and d=1/2at 2 35

Freefall assignment d= how far?d=1/2at 2 0s1s 2s3s 4s 5s v= how fast v=at Write in the seconds at the bottom

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