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Chapter 2: Lesson 3 - Math
Chapter 2: Lesson 3 - Math
Equations
Equations
It will be helpful to have your equation sheet ready. A copy of the equation sheet is under resource materials on this website and on google classroom. It can also be found HERE.
Equation for Displacement:
Equation for Displacement:
By using equations that we already know v=d/t, we can move the equation around to find out what we want to know. If we needed to solve for displacement, ∆d, then we could just multiply both sides by ∆t to get ∆d=v*∆t.
The bar over the v in the picture stands for average. It is read v bar. (I told you physicists were lazy... they can't even say the word average.) While this is a way to write the equation for average velocity, we will not use the bar in CP Physics.
Bowling Ball Demonstration:
Bowling Ball Demonstration:
Watch the video below to see the bowling ball demonstration. In this demonstration, we rolled a bowling ball and started the stop watch when the bowling ball crossed the starting line, where d=0 m. The stop watch was stopped when the bowling ball crossed the 2 m, 4 m, and 6 m mark. The times and distances were recorded below.
The split times are the times in between the orange distance markers on the floor. That is why we need to add the 0-2 m time to the 2-4m time to get the time from 0-4 meters.
We now need to use the distances and times that we collected to calculate the average speed for each distance.
Watch this video to see how we will calculate the velocity of the bowling ball with the data that we collected.
Converting Units:
Converting Units:
To convert units you can use the factor-label method. In the factor-label method, units can be changed by multiplying by a factor of unit magnitude, or a form of one.
There are common conversions listed on your equation sheet. 100 cm = 1 m, 1000 m = 1 km, and 1000 g = 1 kg. In physics, it is always a good idea to convert all of your units to the three fundamental units that you learned about in lesson 1. It will never be wrong to convert a unit to a fundamental unit, but it may be wrong if you do not convert a unit to a fundamental unit. When it doubt, always convert to m, kg, or seconds.
Watch this video to see how you can convert units using the factor label method. You do not have to use this method. If you know how to convert units another way, you are more than welcome to use it.
You just have to know how to convert units.
Click here to access the paper that I used in the video. Try the conversions on your own first, then watch the video to see if you are correct!
Problem Solving Strategies:
Problem Solving Strategies:
What is not negotiable in physics are the five steps that you need to follow to solve a math problem. The math in this chapter is very straight forward and I understand that you can probably give me an answer off the top of your head. Think of the math in this chapter as practice on using the problem solving strategies, not just answering the physics math problem. You have the equation sheet so you have seen all the equations that we will be using this year. Future math problmes are not as simple as v=d/t and we need a strategy to tackle ALL the physics problems.
Watch the video below to see the problem solving strategies in action. I went over two sample problems from this chapter. Click here to access the paper that I used in the video. Try the math questions on your own first, then watch the video to see if you are correct!
Problem Solving Strategies:
Problem Solving Strategies:
These steps must be used EVERY time you complete a math problem in Honors Physics A and B.
Write down all that is given in your problem and what the equation is asking for.
Write the equation down that you will be using. You will always have access to your equation sheet.
Plug in the information from the givens into your equation.
Use a calculator to find and write the correct answer.
Write down the correct unit to the right of your answer.
Check Your Understanding:
Check Your Understanding:
Try solving the two physics problems below by using the five steps in the first question and conversion of units in the second question. Click on the down arrow when you have your answer to check to see if you are correct. You do not need to use the five steps when you are converting units.
A high school athlete runs 100 m in 12.20 s. What is her average velocity in m/s?
Given: d=100m
t=12.20 s
v=?
v=d/t
v=100m/12.20s
v=8.20 m/s
2. Using your answer from above, what is her velocity in km/s?
8.20 m/s * 1km/1000m = .0082 km/s
You have finished Lesson 3!
You have finished Lesson 3!
Be sure to head over to google classroom and fill out the exit pass.
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