Chapter 11MOTION

VIDEO

http://www.youtube.com/watch?v=uDP7Pty8Qnw

@ 34 secondsDrag Race

11.1DISTANCE AND DISPLACEMENT

System of objects that are not moving with respect to each other

Frame of Reference needed to describe motion accurately and completely

Ex: Moving car and a tree on the side of the road

Relative Motion: movement in relation to frame of reference

FRAME OF REFERENCE

Distance: Length of path between 2 pointsDisplacement: direction and distance in a straight line

from the starting point

DISTANCE AND DISPLACEMENT

Vector: quantity that has magnitude and directionAdd displacements using vector additionWhen 2 vectors have same direction add themWhen 2 vectors have opposite directions subtract

them

COMBINING DISPLACEMENTS

Resultant Vector: sum of two or more vectors

COMBINE DISPLACEMENTS

1. What is a frame of reference, how is it used to measure motion?

2. How are distance and displacement different?

3. How are displacements combined?

SECTION REVIEW QUESTIONS

Horse Head Nebula (interstellar clouds of dust), found in Orion, dark portions are thick dust, pinkish glow is from hydrogen gas

11.2SPEED AND VELOCITY

The ratio of the distance and object moves to the amount of time an object moves

How far an object goes in a certain amount of time

S = D/T or V = D/TAvg. Speed = calculated for the entire tripInstantaneous speed = calculated at a point

in time

SPEED

MATH TRIANGLE

S

D

T

S =D/TD = S x TT = D/S

Nissan GTR 11.2 Sec @ 121.8 miles/hour How long was the race?

D=S * T 121.8 miles/hour = .03 miles/secondD = .03 miles/second * 11.2 seconds = .38

miles

MATH PRACTICE

Description of both speed and directionVelocity is a vectorWhy is velocity a vector?

Has both magnitude (size) and direction.Changes in velocity can be: in speed, direction or in both

VELOCITY

Decide in the scenarios below if there is a change in velocity:

A car is going 45 mph and stops at a stop light.

A driver going down a straight portion of the highway is using cruise control to remain at a constant speed.

A child is riding a merry go round.

VELOCITY PRACTICE

MATH TRIANGLE

V

D

T

V =D/TD = V x TT = D/V

Two or more velocities may be added by vector addition

A boat is heading down river at 20 mph, the river is flowing at 3 miles per hour, what is the combined velocity?

23 mph

COMBING VELOCITIES

Distance time graphs show velocity

DISTANCE-TIME GRAPHS

0-60 in 3 seconds (acceleration)Reaching speeds in upper 60’s (velocity)

11.3ACCELERATION

ACCELERATION

Acceleration is a vectorChanges in speed direction or both (change in

object’s velocity)Can be positive change in speed, increasing speedCan be negative change in speed, decreasing speedExample: Airplane taking off is positive acceleration,

airplane landing is negative acceleration

F-16

Changes can be in direction Merry go round is constant acceleration (constant speed

always changing direction)Changes can be in both direction and speed

Ex: Roller Coaster

ACCELERATION

Free Fall: movement of an object toward Earth due to gravity

Unit is: m/s2

Objects on accelerate towards Earth at a rate of 9.8 m/s2

Constant Acceleration: steady (constant) change in velocity

Instantaneous Acceleration: How fast a velocity is changing at a specific instant

ACCELERATION

http://www.youtube.com/watch?v=AvKJ9DcaJ8M&noredirect=1

CALCULATING ACCELERATION

Vf - Vi

A t

Slope of a speed-time graph is acceleration

GRAPHING ACCELERATION

Acceleration is a curved line on a distance-time graph

GRAPHING ACCELERATION

http://www.youtube.com/watch?v=q4Z7M4bPfHk

Red Bull Jump