Vectors

We started the day off by correcting the Kinematics pracitce quiz.

Then we started our new unit on Vectors.

The difference between vectors and scalor quantities is

Vectors

• need a direction

Scalor Quantities

• consist of a magnitue (ex. 6kg or 42m/s)
• the units have to be the same

We then took notes as an intro to vectors. The key points of these notes included.

• A vector is composed of a line segment drawn to scale with an arrowhead at one end.
• The length of a vector symbolizes its magnitude, and the arrowhead its length.
• The direction of a vector always need to be put in squar brakets.

KEY TERMS

Collinear Vectors are vectors that exist in the same dimension.

Equivalent Vectors are a special type of collinear vectors that are equal in magnitude and direction.

Non-Collinear Vectors are vectors that exist in more that one dimension.

We finished off the day practicing drawing vectors.

Brianne is next.

Constant Acceleration Problems

• We started off the class by reviewing how to change a velocity-time graph into a distance-time graph or an acceleration-time graph. The steps are as follows:
  

Distance-Time Graph

1) Find the displacement (area) of different time intervals on the velocity-time graph.

2) Plot several points based on the displacement found in part one.

3) Use your knowledge about velocity to connect the points. Ex: You have two points, one at 2.0s and the other at 5.0s. Look at the velocity-time graph to see if the velocity was constant or changing between 2.0-5.0s. If it was constant, connect the points with a straight line. If the velocity was increasing, connect the points with a positively curved line, etc.

Acceleration-Time Graph

1) Find the slope of several different time intervals on the velocity-time graph. The slope indicates the acceleration of the object.

2)Use the calculated slope to draw your graph. Ex: If you find the slope to be 7.5cm/s from 2.0-5.0s, draw a straight line on the acceleration-time graph at 7.5 on the y-axis from 2.0-5.0 on the x-axis.

3) Whenever there is a straight horizontal line on the velocity-time graph, there is no acceleration.

4) Keep in mind that the acceleration-time graphs drawn at a Physics 30 level don't wouldn't usually make sense in a real life situation.

• Next we moved on to some constant acceleration problems.
  


• Some important points to remember when solving acceleration problems are:
  i) We cannot calculate the answer properly unless the question states that the acceleration is uniform.
  ii) An object that starts from rest has a $V1$ of 0.
  iii) Whenever gravity is acting on the object in question, the object has an acceleration due to gravity of $a=9.8m/s^2$
  iv) When selecting the formula to solve the problem, you should list all of the known variables and the variable that you are trying to solve for. You should be able to select the proper formula simply by looking at which variables are present.
  v) Formulae can be manipulated
  


• We finished off the class by starting a work booklet. The booklet is composed of questions that analyze all of the graphs we have learned about thus far.

Landon is next.

Physics 30 Exam and Dates

Here is the constant acceleration applet we used in class: Here it is!

Here are the answers to the Module 5 Assignment that we worked on Tuesday. HERE

We are writing a Practice Exam in class on Wednesday. This is to be used as an assessment of where you need to improve before Friday's exam. Here is the answer key: PRAC ANSWERS

There is a Kinematics Exam on Friday, Sept. 30. The exam will cover everything we have done so far. Here are the answers to the review: PAGE 1 PAGE 2

If you complete the entire review (you must show work for the multiple choice) and get it signed by a parent/guardian you will receive a bonus mark on your exam.

Good luck!

Acceleration: Constant, Instataneous and the Various Formulae

The class started with Mr.Banow saying a enthusiastic good morning and Jordan talking about the physics behind a toy bow and arrow (unfortunately I was not here for the presentation and so am unable to repeat what was discussed. I'm also assuming Mr. Banow said hi!). Following his presentation he continued to shoot the arrow at Unger.

The previous day the class had begun to work on questions to do with acceleration. The questions were found on page 62, 67 and 69. On page 62, you had to find acceleration using the formula $a=(vf-vi)/(t2-t1)$. On page 67 you not only had to find acceleration but also instantaneous acceleration. That was accomplished by using the formula $a'inst=change in v/ change in t$. On page 69 a velocity vs time graph was given. The question asked that the graph given be converted into another two graphs: a distance vs time graph and a acceleration vs time graph. To create the distance vs time graph, the area of different sections needed to be found to make the points on the graph. To create an acceleration vs time graph the acceleration needs to be calculated [using the formula for acceleration]. The parts with slope indicate acceleration while those that are straight on the velocity vs time graph indicate that this is no acceleration and therefore are found at the x axis on the acceleration graph.



As seen on this graph, there is no acceleration for the first two seconds. On a velocity time graph this would be a straight line. From 2 to 4 seconds this indicates that the acceleration has changed. On the velocity time graph, this part would have a slope. The last section of 4 to 6 seconds indicates that there is no acceleration again. The velocity time graph would be a straight line again.

The class continued after the questions were completed and Mr.Banow turned on the handy dandy smart board. We then looked at constant acceleration formulas. No notes were taken but the class watched an applet to do with a car. The applet showed the different graphs that occured with different motions the car performed such as maintaing a constant velocity, speed and acceleration.



Example 1) A car going constant speed showed the following graphs-*note ignore the numbers from these graphs as they are taken from different source. The shape they create is what is to be observed!

Distance








Velocity








Acceleration





Example 2) When we changed the initial velocity of the car, had an acceleration of (-1) and changed the distance, the following graphs resulted:






Distance







Velocity







Acceleration





The class went back to looking at the formulas that were seen before the applet. The formulas given (found on the handout from yesterday) can only be used if the acceleration is constant! We began to go over the question on a handout dealing with acceleration that had a variety of formulas given. The best choice had to be chosen based on the information given and what you had to solve for. The Graphs on page 69 were announced due for tuesday at the end of class.



Jillian is next :)

Acceleration & the Motion of Cars- 09/23/11

Today's class began with a weekly quiz, which focused on determining velocity and various forms of acceleration through the use of a Velocity-Time graph. From the graph we were asked to find instantaneous acceleration (acceleration of an object at a specific time), average acceleration (the rate of change of an object's velocity per unit of time), instantaneous velocity (velocity of an object at a specific time), and displacement (the change in position of an object) by finding the area of the desired time period. The formulas for the aforementioned vector quantities are as follows:

Instantaneous Acceleration/Average Acceleration- Δv/Δt

Displacement (from a Velocity-Time Graph)- if the area is a triangle: (1/2)bh, if the area is a rectangle: lw

We also had to recognize negative acceleration (which occurred above the x axis and was therefore still a continuation in direction, as compared to negative acceleration which crosses the x axis and would represent a change in the direction).

For the remainder of the class, we continued to work on the Motion of Cars Investigation. With the data collected, we were able to draw graphs and address the accompanying questions; knowledge on the different types of acceleration, velocity, and how to determine displacement were key. We were required to draw Position-Time graphs, which we could create simply by looking at the data collected, as well as a Velocity-Time graph. To create the latter graph, we determine the instantaneous velocity for each point in time using the formula v= Δd/Δt. An example of a Velocity-Time graph can be seen below:

Amanda is next.

Motion of Cars Investigation Part II

Mrs. Smith was our sub today and we went through the instructions for the rest of the class. We were to work on the Motion of Cars Investigation assignment that we had started the day before.

The previous day we had already collected all the data, so we were to analyze it and construct Position-Time graphs for the pull back car and battery operated car.

The information that we collected yesterday was the time inbetween every 6 dot intervals (which was always 0.10 seconds), the displacement between every set of dot intervals, and the displacement between each set of dot intervals in relation to the starting point (0).

By analyzing these graphs, we could see if the cars were moving in uniform motion (moving in a constant direction and speed), or non-uniform motion (changing in direction or speed).

For example:

In this Distance-Time graph, one can see that the object is moving in uniform motion, because it is moving with a constant velocity in a constant direction.

In this Velocity-Time graph, one can see that the object is moving in non-uniform motion because it is not moving at a constant velocity.

The above graphs show how important it is to know the difference between Distance-Time graphs and Velocity-Time graphs. Although they may look the same, they could give you completely different answers.

This assignment and the graphs that we had to complete relates to what we have been learning about recently. For the past few days, we have been learning to analyze and construct Distance-Time graphs and Velocity-Time graphs. In the assignment we also have to do a quick sketch of an Acceleration-Time graph for the pull back car, and recently we have been learning about acceleration.

~Rebecca is next

Motion of Cars Investigation - 9/21/2011

We started off class by introducing a investigation focused on the motion produced by a battery operated car in comparison to the motion produced by a pull-back car. More specifically, the lab requires us to determine if each car produces uniform motion (where the object moves at a constant speed and in an unchanging direction), or non-uniform motion (where the object has an inconsistent speed or a changing direction). We will do this by examing the marks made by the ticker timer as the cars as pull the paper through the timer.


With Daegan and Unger to assist him, Mr. Banow ran through the procedure involved with collecting data for the investigation. Next, in groups of three we began collecting the appropriate data.

Procedure:
First, we had to calculate the number of marks that indicate a time lapse of .10 seconds. Because we know the frequency that we receive is 60. Hz, we can perform the following calculation:

P=1/f
P=1/60. Hz = 0.016666666
0.016666666 x 6 dot intervals = 0.10


Therefore, in a time lapse of .10 seconds, the ticker tape produces 7 marks, and 6 dot intervals.

• Then, in groups of three, we cut a piece of recording timer tape to about 2 m long, and plugged in the recording timer and placed it on one end of the table.


• We inserted the timer tape into the timer, and used masking tape to secure the recording tape to the back of the pull-back car.


• One group member held the loose end of the recording tape, ensuring it passed through the timer correctly, while the second person was responsible for turning the recording timer on, and the third group member was responsible for winding up the pull-back car.


• Once the tape had passed through the timer, the tape was detatched from the car and the same process was done with the battery operated car.


• Each group then began to analyze the markings on each piece of tape, in order to determine what kind of motion each car had.

Lindsey is next.

Average, Instantaneous and Constant Acceleration

To start off class we went over the answers from the Assignment 4 hand-out.

We then went over a new topic... Acceleration!

Average Acceleration- the speed in which something is getting faster or slower.
We can find the average acceleration by using this formula:












or Vf-Vi

Vf or V2 being the final velocity of an object.
Vi or V1 being the initial velocity of an object.

*The SI unit of acceleration is m/s2 (squared) because an object increases speed by Xm/s every second.*

If an object is speeding up it would have a positive acceleration.
If an object is slowing down it would have a negative acceleration.
If an object is travelling at a constant velocity it would have zero acceleration.


Ex.
If you're riding in a vehicle and the vehicle starts speeding up (positive acceleration), you could notice this acceleration by looking at the speedometer but, also you could feel yourself being pulled back.
If the vehicle is slowing down (negative acceleration) you could feel yourself jerk forward.

You can find average acceleration on a graph by drawing a line from one point to another and finding the slope.

Instantaneous Acceleration- acceleration of an object at a specific time.

You can find instantaneous acceleration by drawing a tangent on a curve and finding the slope.

Constant Acceleration- object's velocity changes by equal amounts in equal periods of time.

We finished off class by doing four example questions on acceleration.



Jolene is up next.

Velocity and Time Graphs Part II

Todays class was basically a review of what we did on Friday. We started off by doing the questions out of the text book which asked us to find the displacement and velocity of different graphs.

• Displacement- find the area of the graph by using either 1/2bh (triangle) or lw (rectangle). Once you find the area add them together and that will give you the total dispacement. Remember if the graph has changed direction (gone below the x- axis) the area has to be subtracted.


• Velocity- finding the velocity of a specific point can simply be read off the graph. To find the velocity between two points you must first find the displacement or area of the graph, than by dividing that answer by the amount of time between the points it will give you the velocity.
  

Lastly after we were all finished the questions from the text book we were to complete the Assignment 4 Handout which was based upon the same types of questions.

Paigery Crozon is next :)

Velocity and Time Graphs

We started the day off with taking a quiz on displacement and distance and time graphs.

We learned how to do a velocity and time graph.

From the left of the graph 0-10 seconds shows that it is accelerating. From 10 to 15 seconds it is going a constant speed of 60m/min. From 15 to 30 seconds it is slowing down and at 30 seconds comes to a stop. From 30 - 40 seconds it changes directions and speeds up. From 40- 50 seconds it slows down.

We also learned that to find the displacement you divide the lines and the 0m/min line into triangles and rectangles using the formulas 1/2bh and lw. Once you get the numbers for the sections you addd them together. If the line goes below 0m/min tha you would subtract that section from the secton that is above the line.

We also learned how to switch a distance and time graph into a velocity and time graph and that they would look different but mean the same.

Dana is next.

We started class off with a presentation from Ms. Witte, who showed us the physics behind a tennis ball.

After the presentation we checked out Jeren's blog and discussed it.

After the blog we worked on finishing the questions out of the text book and if this was completed we worked on the sheets given in the previous class. Both the questions from the book and the questions on the sheets were about the slopes and velocities of graphs. To find such things we looked at the graphs and found out the rise over run and did the mathematical equation to find the velocities.

Mr. Rath is next.

Analyzing Position vs. Time Graphs

Yesterday’s lesson started out with Blake doing his presentation on the yo-yo and the physics behind it and how it works. We then moved on to a handout that we had gotten about position vs. time graphs. There were three graphs which were all different. They were connected to the previous classes because we have been looking at position vs. time graphs for awhile now and also some of the formulas we have been using such as displacement and velocity.

The first graph we were given the points and had to construct it ourselves. We then had to do the following things with the corresponding graph:

• Describe the motion of the graph by examining the lines on the grid; whether it was a constant positive velocity or not moving.
• We had to find the objects displacement which can be found by taking the ending positing and subtracting it by the initial position.
• We also then examined the graph to find which part of the trip was the fastest.

The second graph was another distance vs. time graph and with this one we had to:

• Find the velocity over each time interval and then find the average velocity over the entire graph. Velocity is equal to distance divided by the time and average velocity is equal to total distance divided by total time.

The last graph that we looked at was a distance vs. time graph which had a curve in it. We had to do the following:

• Find the instantaneous velocity at PT. A where you draw a tangent line so it barely touches the point on the graph. We then find 2 points such as (3,4) and (5,6). We will then find the slope of the graph which is equal to y2-y1 divided by x2-x1.
• The last part we had to find the average velocity of the graph where we had drawn a line straight across point b to point d, found 2 points on the line and found the slope of those points and that had given us the answer.

There was then some textbook questions at the end

Position vs. Time Graphs Sept. 13 2011

The main part of the lesson today was about position vs. time graphs but at first we did an example equation that dealt with the lesson from the day before. It was connected to speed and velocity but was a bit harder than the others we had done before. The question had three velocities and times in different directions and wanted the average velocity of the three. We needed to find the displacement of the three velcoities then divide by the total time to get the answer.
Next we looked at position and time graphs. Looking at these graphs connected back to what we had worked on last week. We had to graph the speed of and object and analyze the slope of the line. Today we looked at some of the basic rules with position and time graphs. We leanred that the slope of the line gives us the object's velocity which we had figured out last week. We learned that the slope of a line segement between two points on the line tells us the average velocity during that period of time. We also learned that the slope of the tangent touching a certain point on the line tells us the instantaneous velocity at that certain time. We also looked at a few different types of position vs. time graphs. There is the zero velocity graph which is a horizontal line across the graph telling us that the object is not moving. Another graph is the constant velocity graph which is a straight line that shows us the velocity does not change as the object moves. Another example of a position vs. time graph is the continuously changing velocity graph. This graph is a parabolic graph and the average speed of the object graphed by this line has changing velocity as it moves.

unger

Hi I'm Unger