Physical Science

Physical ScienceChapter 11 Part 1Non-accelerated MotionChapter 11.1-11.2Frame of ReferenceA system of objects that are not moving with respect to one anotherA reference point or systemBASICALLY . Something unchanging to measure things fromGood frames of reference for measuring the motion of a carThe Earth, the road, buildings, treesBad frames of reference for measuring the motion of a car.Clouds, other cars on the road, bikers, flying birds

Relative MotionMovement in relation to a frame of referenceAll Motion is RelativeThis means all motion is based on someones or somethings perspective ExamplesSchool bussesCars on highwayLabQuest

Relative Motion

Or a more recent example Measuring DistanceLength of a path between two pointsWhen an object moves in a straight line, the distance is the length of a line connecting the starting point and the ending pointSI Unit metersOther options- km, mi, cm

DisplacementDistance with a directionDistance 5 kilometersDisplacement 5 Kilometers NorthHow much an object is displacedWhen objects travel in a straight line the magnitude (amount) of the displacement is equal to the distance travelledWhen an object does not travel in a straight line, distance and displacement will be different

VectorsVector Quantities Have magnitude and directionScalar QuantitiesOnly have magnitudeVector quantities can be represented with arrows of a scaled lengthLength shows magnitudeArrow shows direction

3 km3 km3 km + 3 km = 6 kmVectors & ScalarsVectors- Have Magnitude & DirectionScalars- Have only MagnitudeExamplesExamplesDisplacementDistanceVelocitySpeedAccelerationMassForceTimeDisplacement in a straight line4 km7 km4 km + 7 km = 11 km8 km5 km8 km - 5 km = 3 kmDisplacement that isnt on a straight PathResultant Vector (red) vector sum of 2 or more vectors 1 km2 km1 km3 km5 kmFinding Distance Using Scalar Addition 1+1+2+3 = 7 km

Finding Displacement using Vector Addition = 5 km NEThese two vectors have the same ________________ and opposite ________________. These two vectors have different ________________ but the same ________________. These two vectors have the same ________________ AND the same ________________.

average SpeedInstantaneous SpeedSpeed at a given moment of timeWhat the speedometer on a car reads

Constant SpeedWhen speed is not changingInstantaneous speed is equal to average speed at all timesNOT Speeding up or slowing down

Only ways to change speed is to speed up or slow downAverage SpeedConstant SpeedInstantaneous SpeedThe Average speed over some timeMaintaining the same speed all the timeSpeed of an object at a particular moment in timeVelocitySpeed AND direction that an object is movingVector Quantity+ or sign indicates which direction the velocity is+ means North, Up, East, or to the Right- means South, Down, West, or to the leftSometimes multiple velocities can affect an objects motionSailboat, airplanesThese velocities combine with Vector Addition

Speed vs. VelocitySpeed tells how fast something is movingEx. 100 km/hrVelocity tells how fast something is moving and its directionEx. 35 mph North

Can an object move with constant speed but have a changing velocity?

Can an object move with constant velocity but have a changing speed? 2 ways to change Speed 3 ways to change VelocitySpeed UpSpeed UpSlow DownSlow DownChange DirectionaccelerationAcceleration The rate at which velocity changesCan be described as .Changes in SpeedChanges in DirectionOR change in both Speed and DirectionVector QuantityUnits are meters per second per second or m/s2

3 Way to AccelerateSpeed UpSlow DownChange Direction

Can an object moving with constant speed be accelerating?

Devices in Cars that lead to acceleration

Calculating AccelerationExample

Graphs of motionMotion can also be depicted very well using graphsTwo types of graphsDisplacement vs. time (D-t) graphsVelocity vs. time (V-t) graphs

Straight,upward line on D-t graph means constant velocityStraight,upward line on a V-t graph means constant accelerationDisplacement (m)D-t graph of constant vDisplacement increases at regular intervals, so constant velocityGraph below Increases displacement by 5 meters every sec.To find vel. on a disp.- time graph, find SlopeSlopeTells the rate of increase of the y-value as you move across the x values for any graphSlope = rise / runIn other words how much the graph goes up divided by how much the graph goes acrossSlope tells us properties of the motion being depictedOn a displacement time graph slope = velocityOn a velocity-time graph slope = accelerationRun = 5Rise = 25Rise/run=slope= 25/5 = 5 m/sIf you took slope of smaller sections of the graph you would get the same answer since v is constant

Velocity- Time graphs v v. t graphs may look the same as some D v. t graphs, but the motion they describe can be very different because they deal with velocity, not distance.

**The slope, of a Velocity v. Time graph indicates Acceleration**.

Distance-time graph of changing velocityTime (s)Displacement (m)0018211318415525What is v for 0-1 sec.?? What is v for 0-2 sec.??What is v for 3-5 sec.?? What is v for 0-5 sec. ??Distance-time graph of constant accelerationParabola.. If + acc, line keeps getting steeper and steeperdtAvg. velocity from 0-1 sec. ? 4 m/sAvg. vel. From 3-4 sec? 16.5Acc. From 2-3 sec? 7 m/s2

Velocity vs. Time graph of constant acceleration

Velocity (m/s)Speed-time graphSlope = rise/run Rise = 16 Run = 4Rise/run = 4 m/s = acceleration

Position time GraphSlope = rise/run Rise = 50 Run = 5Rise/run = 10 m/s = speed

Free Fall AccelerationAs objects fall toward the Earth they are accelerating at a rate of 9.8 m/s2 downwardWe can usually round 9.8 m/s2 to 10 m/s2 Objects in free fall will gain 10 m/s of speed for every 1 second it is fallingTime (sec)Instantaneous Speed (m/s)Acceleration (m/s2)001011010220103301044010Free Fall AccelerationObject is in free-fall any time it is ONLY under the influence of gravityIncluding when something is thrown upwardsAll objects (regardless of mass) fall at the same rate on Earth, when air resistance is ignoredTime (sec)Instantaneous Vel. (m/s)Acceleration (m/s2)0+30-101+20-102+10-1030-104-10-105-20-106-30-10Ball thrown upward with initial velocity of +30 m/sThe slope of ______________ lines indicates ______________.

When tangent lines become ______________ with time, this means that the object is ______________ up. (It was originally at ______________.)

The object is moving ______________ from the reference point with time.

The tangent lines are getting ______________ steep with time.

This means that the object is ______________ down (to a ______________).

Because distance is ______________ with time, the object is moving ______________ from the reference point.

The object has ______________ acceleration.

The object moves with _________________ velocity.

What motion does this graph represent?

This object is at ______________ because its velocity is always ______________.

This objects velocity is _________________ with time.

This graph shows ________________ acceleration (one _____________).

This object is _________________ up.