Scientific Methods. SI Units. The base units we will use in this course:. Metric Prefixes. Metric Prefixes are used on SI Units to make it easier to describe the values. Unit Conversions. To convert between units we use a fun little process called Dimensional Analysis .
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The base units we will use in this course:
Metric Prefixes are used on SI Units to make it easier to describe the values.
When we make measurements, each measurement only has a certain degree of certainty.
Measurements can only be made to a certain decimal place.
The last decimal place is always an approximation.
This is why we need to use Significant Figures.
When we are dealing with really BIG or really small numbers, sometimes we need to describe them using scientific notation.
Just remember that the exponent on the 10 tells you how many places the decimal is moved to the right or left.
Positive exponent->RightNegative exponent->Left
There will only be one integer to the left of the decimal point.
Write in scientific notation:
We will be using a lot of Algebra in Physics… which is good because you’ve had 2 years of it, right?
And you will see plenty of fun equations like these:
Whenever we are working problems with equations we will need to solve for the variable we are looking for before we substitute numbers!
Solve this equation for G.
Our goal is to get G by itself on one side of the = sign.
Remember the golden rule of algebra: you have to do the same thing to both sides in order to cancel units!
This means if you multiply by a variable on one side you have to multiply it on the other side!
Solve this equation for G.
First, multiply each side by r2to move it over to the left.
Divide by (m1m2) to get rid of both variables
Flip it so that G is by itself on the left side.
Wasn’t that easy?
Remember: This should all be a REVIEW!
Graphs have 2 axes: the horizontal (usually called ‘x’) and the vertical (usually called ‘y’)
Graphs will be named according to what is plotted (it goes by the general form “Y” vs. “X”
Each axis should always be labeled and include the proper units.
What is the slope of the line in the graph?
Slope (m) = (∆y / ∆x) m = (y2 – y1) / (x2 – x1)
First, select two points that are far apart
Plug values into the equation:m = (30 – 10) / (14 – 4)m = 2
So, the slope is 2, but what are the units, and what do they mean?
In this case, the units would be (smiley faces / puppies) or /p
And this tells us that you would get 2 smiley faces for every puppy you see!
Two variables are said to be directly related when one variable increasing causes the other to increase as well.
Two variables are indirectly (inversely) related when one variable increasing causes the other to decrease.
Occasionally, you might run into a graph that is not linear, like the one below.
This presents a problem, because we cannot do much of an analysis with a curved line. This means we need to linearizethe graph (turn it into a straight line)
First, you need the equation for the line. For this one, it is conveniently y = x2, or p = t2
To linearize the data and obtain a straight line, we will need to plot a Position vs. Time2 graph instead.
Let’s do a real world example:
Timmy is a geek and is having a hard time making friends…
He just wants to be friends with the cool kids…