Physical Science Chapter 11 Motion Chapter pg.328 11.1 Distance and Displacement 11.2 Speed and Velocity 11.3 Acceleration Richard E. Clemons M.S. MNHHS MARCH., 2008

Motion Are we in this room in Motion? Y or N Both answers are correct due to the following reasons; A) no because our position to the floor, walls, and ceiling is not changing B) yes, as a part of the earth we are rotating and revolving constantly

11.1 pg.328 Distance & Displacement All forms of motion has to be judged by an outside factor The concept is based on a frame of reference or a reference object These reference items are best chosen as items that under NORMAL conditions can not move

Reference A reference object is any object that we can use to define determine if a change in an objects position has occurred Any object that can move under normal conditions is NOT the best choice to use for determining motion Best items; those that normally Stationary usually the ones that are attached to the Earths surface Examples; trees buildings road signs

Relative motion All motion is relative until proof of that movement can be presented That is a change in the objects position as compared to a reference item attached to the earth This motion can then be measured for distance moved and the time it took that distance to be covered

Distance Is the measured value that connects two points when in a straight line the calculation is simple A line is shortest distance between two points Standard unit for length (dist) in science is the METER and we add prefixes for longer or shorter values

SI / Metric system for distance Base unit METER Prefixes Larger value Giga = billion Mega = million Kilo = thousand Smaller value Deci = 1/10 Centi = 1/100 Milli = 1/1000

Quantity Information that is obtained and provides us with specific data places for analysis This data provided falls into two categories A) Scalar quantity B) Vector quantity

Scalar Quantity A description of an item that is focused on One factor only The focus is on MAGNITUDE Magnitude is a measurement value, thus it must have a number an label Single dimension (definite quantity) Time, temperature, length, mass, direction

Vector Quantity A description of an item that contains TWO components of information Like a scalar quantity it also contains a magnitude value Unlike a scalar quantity a vector also includes a second component, direction Vectors are then Magnitude with Direction

Displacement This item is a two part factor for motion A) distance B) direction When both distance and direction are combined it can provide a large amount of information 5Km or 5Km to the East Which one is best for providing a direction to a stranger to your area?

Resultant vector The resultant vector is the vector that is produced that equals the sum of the vectors involved in the problem That is, gets you from the starting point to the ending point in the shortest distance or the new velocity and direction caused by the interaction of multiple vectors on an object

Resultant vector There are four methods that we will focus on for solving multiple vectors of interaction A) adding B) subtracting C) Pythagorean theorem a2 + b2 = c2 written as r2 = a2 + b2 D) law of cosines r2 = a2 + b2 – 2abcos(theta)

Solving vectors Adding Subtract Combine the two values by adding if and only if the parts are going in the same direction Subtract Combine the two values by subtracting if and only if the parts are going in the opposite direction

Solving vectors Pythagorean theorem Law of Cosines If the two parts form a right angle and the finishing side completes a right triangle Law of Cosines Use for any vector that does not fit the other styles and when the final side is added you have created a triangle that is acute and/or obtuse (any style other than a right triangle)

Distance: Displacements Along a Line Figure 3 Distance: Displacements Along a Line

Distance: Displacements Along a Line Figure 3 Distance: Displacements Along a Line

Distance: Displacements Along a Line Figure 3 Distance: Displacements Along a Line

Distance: Displacements Along a Line Figure 3 Distance: Displacements Along a Line

Distance: Displacements Along a Line Figure 3 Distance: Displacements Along a Line

Speed or Velocity sect 11.2 pg 332 The math portion is the same equation Rate = distance / time That is how fast is equal to total distance divided by total time Since direction will be necessary at some time the term velocity is a better choice So VELOCITY (V) = DISTANCE (D) / TIME (T)

Calculating Average Speed Section 11.2 Calculating Average Speed

Calculating Average Speed Section 11.2 Calculating Average Speed

Calculating Average Speed Section 11.2 Calculating Average Speed

SLOPE pg 334 On a graph the velocity or rate of motion can be found by finding the slope of a line Slope = rise / run Slope = change in Y’s/change in X’s

Distance-Time Graphs for Motion of Three Cars Section 11.2 Distance-Time Graphs for Motion of Three Cars

Acceleration sect 11.3 pg 342 Acceleration is the rate at which velocity changes against time How fast the rate is increased or decreased or the direction changes Acceleration equals final velocity minus starting velocity divided by time A = VF – VI / t

Acceleration Summary Any change in the following can technically be a form of acceleration Faster velocity Slower velocity Change to direction

Acceleration Name three items in / on a car that can control acceleration Gas pedal (accelerator) Brake pedal (decelerator) Steering wheel (change direction)

Measuring Acceleration Section 11.3 Measuring Acceleration

Measuring Acceleration Section 11.3 Measuring Acceleration

Measuring Acceleration Section 11.3 Measuring Acceleration

acceleration graphs pg 346 Figures 16 and 17 acceleration graphs pg 346

Distance-Time Graph of Accelerated Motion Figure 18 Distance-Time Graph of Accelerated Motion

Average or Constant or Instantaneous Average is the comparison of TOTALS; total distance / total time Constant (uniform) NO change in the rate or direction Instantaneous what is happening at a specific moment (how fast when you look at the speedometer of the car)

Equations Velocity *V=d/t *d=v*t *t=d/v Vectors *Add (same) *subtract (opposite) *Pythagorean c2= a2 + b2

Equations Slope *Slope = rise/run *slope = y2 – y1 / x2 – x1 Acceleration *a = VF – VI / t *t = VF – VI /a *v (change) =a*t