Motion and Its Applications UNIT ONE

Motion Part of the everyday physical world We learn to walk, run and drive without really understanding the physics of motion We have an intuitive idea of motion and its effects and causes

Unit 1: Motion and Its Applications copy Motion Movement of an object from one place to another, as measured by an observer Two objects are in motion with each other if the straight-line segment between them changes in: Length Direction Or both

Are the carts in motion with reference to each other? Explain. Two golf carts are travelling at the same speed in the same direction along a straight level path. Are the carts in motion with reference to each other? Explain. 8/6/2018

Uniform Motion Non-Uniform Motion copy Uniform Motion movement at a constant speed in a constant direction (rare!!) Non-Uniform Motion Movement that involves changes in speed or direction or both

Uniform or Non-Uniform? A) A rubber stopper is dropped from your raised hand to the floor. B) A car is travelling at a steady rate of 85 km/h C) A motorcycle rider applies the brakes to come to a stop 8/6/2018

Physical Quantities Two Types: Scalar Quantities copy Two Types: Scalar Quantities Only have a size and a unit . 7 days, 2 m. 3 kg Vector Quantities Have a size, unit, and a direction. 3 m [E] , 15 N [S] **note the square brackets

Vector or Scalar? 50 km/h 6 km/h [N] 2000 kg/m3 6 centuries 20 m/s [down] 800 kg 23 m

Distance, Position and Displacement copy Distance, Position and Displacement Distance is the total length of the path travelled by an object Represented by ∆d (∆ means ‘interval of’)

Distance For example, if you walk directly from home to the school in a straight line, you will travel a distance of 500 m If you walk from the school to the library and then return home, you will travel 1900 m (700 m + 1200 m)

Position Is the location of an object relative to a reference point copy Position Is the location of an object relative to a reference point It is a vector quantity, so direction must be indicated Symbol =

Position For example, if home is your reference point, the position of the school is 500 m [E] Note: the magnitude of the position is the same as the straight-line distance (500 m) from home to school, but the position also includes the direction

Displacement Refers to the change in position of an object from its initial position to its final position It is a vector quantity Unlike position, displacement does not require a reference point Symbol = ∆

Displacement For example. If you walk directly from home to school your displacement is 500 m [E] (500 m[E] – 0) If you then walk from the school to the library and then return home, your total displacement will be 0 (500 m[E] + 700 m[E] + 1200 m[W] Recall: displacement is the CHANGE in position

Practice What is your (i) distance and (ii) displacement if a) you walk from the school to home and then to the library? d= 1700 m; = 700 m[E] b) you walk from home to the school and then to the mall? d = 2000 m; = = 1000 m[W] A dog, practicing for her agility competition, leaves her trainer and runs 80 m due west to pick up a ball. She then carries the ball 27 m due east and drops it into a bucket. What is the dog’s total displacement? = 53 m[W]

Check Your Understanding Textbook: pg 13, #1-4 (photocopy)

Adding or Subtracting Vectors in a Straight Line

Adding/Subtracting Vectors in a Straight Line copy Adding/Subtracting Vectors in a Straight Line A vector quantity is represented on a diagram by a line segment with an arrow at one end to indicate direction We can add vectors together in two ways: 1. Graphically - Draw both vectors to the same scale and connect them from tip to tail - Draw a vector from the tail of the first to the head of the second vector, label it R (from where you started, to where you ended up) - Measure the length of the resulting vector Tail Tip

Eg. 6 km[E] plus 5 km[W] 1 cm = 1 km copy Eg. 6 km[E] plus 5 km[W] 1 cm = 1 km The resultant vector is 1 km[E] (measured)

- assign each direction as positive or negative copy 2. Algebraically: - assign each direction as positive or negative Eg. 6 km[E] plus 5 km[W] Let [W] be negative and [E] be positive Displacement = 6 + (-5) = +1 = 1 km[E]

Try these…. Solve the following graphically and algebraically 3 km[E], then 15 km[W] 11 km[E], then 15 km[E], then 10 km[E] 1 km[W], then 2 km[E], then 2 km[W] 5 km[S], then 2 km[N], then 3 km[S]

Text pg. 13, #5 and 6 (photocopy)