ch. 11. 1. truefalsestatementtruefalse a frame of reference is objects moving with respect to one...
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Distance and Displacement
Ch. 11. 1
True False Statement True False
A frame of reference is objects moving with respect
to one another
Distance is the length between 2 points and the
direction
Displacement is the added length of all points and the
direction
To add straight displacements you add the
vectors
To add non straight lines you use the resultant vector and Pythagoreans theorem
Frame of Reference Helps describe
motion accurately and completely
A system of objects NOT moving with respect to one another
Relative Motion Movement in
relation to a frame of reference
Ex: Train▪ Platform- people on
train are moving▪ In train- people are
not moving
Measuring Distance
Distance= the length of a path between 2 points
SI Unit- meterkilometer- large distancecentimeter- small distance
Measuring Displacement
Displacement= direction from start point and length of a straight line from start to end point
Travel 5 blocks north of the bus stop
Combining Displacements
Vector= quantity that has magnitude and direction Magnitude= size, length, or amount Shown as arrows on maps/graphs
Add displacements by adding vectors
Combining Displacements-Straight Lines
Add magnitudes if 2 vectors have same direction
Ex: 1st car magnitude= 4km(pg 330)
2nd car magnitude= 2 kmBoth traveling same direction
= ____ km displacement Opposite traveling direction
= ____km displacement
Combining Displacements- Not straight lines
Add total distance Draw resultant vector
Vector sum of 2 or more vectors Also displacement
Pg 331- Walked 7 blocks Displacement= 5 blocks
NE
*Integrating Math-Pythagorean theorem
a2 + b2 = c2
Find distance traveled and displacement
Speed and VelocityCh. 11.2
True False Statement True False
Speed is distance/time and the SI unit is m/s
Velocity is speed with direction and the SI unit is
m/s2
Velocity has the same formula as speed
Because velocity is a vector we can use Pythagoreans
Theorem
The slope of a distance time graph is velocity
Speed
Speed= the ratio of the distance an object moves to amount of time the object moves
SI Unit- meters per secondm/skm/h
2 Types of Speed
2 Types of Speed
AVERAGE SPEED
Speed computed for entire duration of trip
v = d t
INSTANTANEOUS SPEED Speed at a particular
instant Can tell you how long
your trip will take Speedometers
Calculating Speed Practice
While traveling on vacation, you travel 35 km in 0.4 hours, then 53 km in 0.6 hours. What is your average speed?
1. Given InfoTotal distance:Total time:
2. Solveneed speed
3. Plug and chug
4. Check
Math Practice pg 333
1.
2.
Graphing Motion
Slope of a line on a distance-time graph is speed
Pg 334 Calculate slope of A= B= C=
Velocity
Velocity= the speed and direction in which an object is moving Description of BOTH speed and direction Vector
Change in velocity Change in speed, direction or both
Race car traveling 120 km/h
Speed, direction, velocity?
Combining Velocity
2 or more velocities added by vectors
River= 5 km/h Boat= 12 km/h Total velocity=
pg. 337
River= 5 km/h Boat= 12 km/h Total Velocity=
AccelerationCh. 11.3
True False Statement True False
Acceleration is a change in speed, direction or both
a = vi – vf t
An object slowing down is accelerating
An object in a circle, at constant speed is
accelerating
Acceleration can be a time-speed graph or distance-
time graph
Acceleration
The rate at which velocity changes Changes in speed, direction or both vector
Acceleration
CHANGE IN SPEED
Increase or decrease in speed
Free fall- movement of object toward Earth due to gravity(9.8m/s2)
SI unit- m/s2
CHANGE IN DIRECTION
Speed can be constant, but a change in direction yields acceleration
Acceleration
CHANGE IN SPEED & DIRECTION
CONSTANT ACCELERATION Steady change in
velocity
Calculating Acceleration
Acceleration Practice
A ball rolls down a ramp, starting from rest. After 2 seconds its velocity is 6m/s. What is the acceleration of the ball?
1. Given InfoTime-Vi-Vf-
2. Plug and Chugacceleration-?
3. Check
Math Practice pg 346
1.
3.
2.
4.
Graphs of Acceleration
Slope of speed-time graphs is acceleration
Change in speed divided by change in time
Graphs
SPEED-TIME GRAPH
Linear graphs
DISTANCE-TIME GRAPH
Nonlinear graphs
Instantaneous Acceleration
How fast a velocity is changing at a specific instant
Review
Review
Motion
displacement
acceleration
directionChange in speed