XDM Prodns 1

Physics: The Study of Motion

We are going to explore the science of motion. The study of motion is very important in our lives, though it may involve some math!!!

1. Motion Language:

2. Using our math skills A. Calculating the time interval: If you are running to my classroom to hand in your homework and you leave the door of the school at time 0 (ti) and you hand in your homework at tf (time final) how do you calculate the time interval? à It’s how long it takes to get from ti to tf , which is tf – ti Sample Questions: 1. If Cade is going to get a slurpee and pick up a coffee for Mr. Eckert, calculate his Δt if he leaves 711 at 2:15:31, and then gets Eckert’s coffee at 2:22:41.

2. If I’m walking my dog, Duke, around the block, calculate my Δt if I leave my house at 7:15:41 and return to my house at 7:45:51

Scalar Quantities (Amounts) that are measured that describe the magnitude (how big) but do not include the direction

Vector Quantities which are measured that describe the magnitude of the movement and the direction. Vector Symbols have arrows above them to let you know there is direction involved

Distance Scalar quantity that describes the length of a path between two points (In metres)

Position Is a Vector quantity that describes a specific point relative to a reference point. In other words how far and which direction someone is from you or another object.

Time Interval Change in time. Usually measured in seconds. Δ Delta. The symbol for change in quantity.

XDM Prodns 2

B. Distance Looking at the same equation you can calculate the distance travelled by using this equation: Δd = df - di

This has to do with a reference point. This is compared to something, for example: 1. Mr. Eckert starts to walk his dog 20m (E) from a telephone pole he walks past the

telephone pole 10 m (W) before his dog falls over and is too tired to walk on. How far has he traveled?

2. Mr. Gallacher is going to Starbucks for a coffee. He starts out 100m (N) from Starbucks and get’s his coffee. He ends up back at the school 100m (S) from where he started. What is his distance traveled?

C. Displacement This is a vector quantity. Which means it has direction and magnitude. What is the difference between distance and displacement? Distance is how far you travel, and displacement is how far you are from your start place. In other words, if you travel in a 10km circle back to your original start place, your displacement is zero, but you distance is 10km. 3. Mr. McIver is golfing. He lines up a putt and his position at the start is 5.5 m (E) of the

hole. When he hits it he misses and it rolls 4.4m (W) of the hole. A). What is the total distance travelled by the ball? B). If he then sinks the 2nd putt what is the displacement of the ball from the start?

XDM Prodns 3

Provincial Exam Question:

3. Plotting Points on a Graph A. X and Y axis: Which one is which? B. The Quadrants: I, II, III and IV C. Plotting Points! Plot the following: -3, 3 3, 4 4, -5 5, 6

Distance vs Displacement What is the distance from A à D? ___________________ What is the displacement from A à D? ___________________

XDM Prodns 4

Looking at Displacement Vs Time Graph: Let’s answer some questions about this together: a. Between 0-3 sec the total distance is _________ the displacement is _____ b. Between 3-11 sec the total distance is __________ the displacement is ______ c. Between 11-16 sec the total distance is _________ the displacement is ______ d. Between 16 and 18 seconds the total distance is _________ the displacement is ______ e. Between 18 and 29 seconds the total distance is _________ the displacement is ______ f. Let’s label the graph is positive directions and negative directions.

XDM Prodns 5

4. Uniform Motion: A. Uniform Motion When something moves consistently at one speed it can be called uniform motion. This is because it covers the same amount of distance over the same time interval. Example: Now let’s set it up in a chart: What does it look like in a graph?

B. Best Fit Lines: A best fit line is a smooth curve or line which generally fits the shape of the graph: Example

Time (hr) Position (km) O O 1 10km (+) 2 20km (+) 3 30km + 4 40 km + 5 Stopped 6 Stopped 7 30km + 8 20km + 9 10km+

XDM Prodns 6

5. Slope: The Slope of a graph refers to whether the line is horizontal or goes up or goes down. Think of the x axis as the point of reference.

A. Positive Slope:

When a position time graph slants up to the right it is said to have positive slope:

B. Zero Slope: On a position time graph an object at rest, which is not moving is represented by a zero slope:

C. Negative Slope: A negative slope graph slants down to the right. If you are talking about a position time graph, the object goes past it’s goal position. This is like a golf ball rolling past the hole.

6. Calculating Slope: Rise = Slope Or for you math folks Y2-Y1 Run X2-X1 That means it is the change (Δ) in rise divided by the change (Δ) in run. How far does it go up or down? How far does it go left or right?

XDM Prodns 7

7. Velocity: Changing the position you are in! Velocity is the displacement change of an object’s position over time. The Unit for velocity is m/s. Speed is the same thing as velocity but without the direction. So two escalators can have the same seed but different velocities because they are travelling in different directions. 8. Average Velocity: Average velocity is the rate of change in position for a time interval. This includes a direction. The symbol for this is Vav 9. Calculating Average Velocity using Slope: Slope = Rise Run

= Δd Δt

A. Calculate the average velocity between 2 and 6 seconds: Vav = Δd Δt 70-20 = 12.5 m/s 6-2

Time (s) X Position (m) Y

0 0 1 10 2 20 3 35 4 45 5 60 6 70

XDM Prodns 8

B. Calculate how far away a skater is who travels 4 m/s (W) for 10 s

Vav = Δd Δt Vav (Δt) = Δd 4m (10s) = 40m W S C. Calculate how much time it would take a biker to travel 300m at 15m/s south. Vav = Δd Δt d. An object has a displacement of 5m E during a 10s interval. If the objects motion were uniform, what would be its displacement during the next 20s time interval? e. Questions to think about! What does positive slope indicate about the object’s movement? What does negative slope indicate about the object’s movement? What does zero slope indicate about the object’s movement?

Provincial Exam Questions:

XDM Prodns 9

10. Acceleration: The rate at which an object changes its velocity is called Acceleration. This is how much velocity it picks up or loses, depending on if the object is slowing down or speeding up. The unit for acceleration is m/s2

A. We can use slope to help us calculate Acceleration This is in a graph called Velocity Vs. Time. In Positive slope: What is the object doing? In Negative Slope: What is the object doing? In constant acceleration: velocity What is the object doing? time

XDM Prodns 10

B. Direction, Direction, Direction! Direction is also important in Acceleration. This is because acceleration has velocity involved in it. i. If a car travels forward and increases it’s velocity it is said to have positive acceleration. ii. If the same car changes it’s velocity in the opposite direction (Slows down) it is said to have negative velocity 11. Calculating Acceleration

a= Δv Δt

Δv = vf - vi Sample Questions: i. What is the average acceleration if a car from the staff parking lot if it races away

and accelerates uniformly at 20m/s for 10 seconds?

ii. A car travelling forward at 25 m/s stops after it runs over a pop can and then backs up at 4 m/s to make sure they got it. a. What is the car’s change in velocity?

b. What is the direction of the car’s acceleration?

iii. Suppose you shoot a paper airplane at 2.5 m/s towards a target. Your paper airplane takes 15 s to get to the target. What is the average acceleration?

iv. Mr. Eckert’s car starts from rest accelerates uniformly to 15m/s (E) in 5 s, what is the car’s acceleration?

XDM Prodns 11

Sample Provincial Exam Questions:

XDM Prodns 12

XDM Prodns 13

12. Gravity and Acceleration: Gravity: when an object falls to the earth it is attracted to the earth by gravity. Gravity is an attractive force which acts between two or more masses. A. When you throw something upwards it has decreasing velocity because gravity is trying to pull it back down towards the earth. B. When the object stops in the air to fall back down it has zero velocity. C. When the object falls back to the earth velocity is increasing because gravity is pulling it

9.8m/s2 back to the earth if there is no wind resistance.

D. Gravity and Air Resistance:

When you drop something that is roughly the same shape it should fall at the same speed regardless of mass. Air resistance is a friction force that opposes the motion of objects that move through the air. E. Acceleration due to Gravity: In the absence of Air resistance (like in a vacuum) things should accelerate at the same speed regardless of mass. g= 9.8m/s2

F. Calculating Acceleration due to Gravity: A = Δv If a= 9.8 m/s2 Δt

Sample Questions: 1. What is the change in velocity as a bird poop falls for 4s and hits your head? 2. A ball is thrown up into the air. How much time does it take to go from 16 m/s to 2.0 m/s

up? 3. Mr. E drops a water balloon out of the top window on Ms. Bola who is innocently standing below. What is the velocity of the water balloon after 3 seconds?

XDM Prodns 14

4. A student is tired of notes in this class. They grab my laptop and drop it out my window. What is the velocity after 5 seconds?

Provincial Exam Questions:

XDM Prodns 15