INTRODUCTION TO PHYSICS GUIDED NOTES NAME:____________________

What is physics? _________________________________________________________________

SI Units

What does SI stand for? ______________________________

Why use SI units? ________________ and ___________________

UNITS AND DIMENSIONS GUIDED NOTES

In table groups, find three different quantities to measure, and take the measurement in SI units. Don’t fill in the last 3 columns yet.

QUANTITY MEASUREMENT DIMENSION UNITS SI OR NOT?

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Unit equivalents

1 Tm = ____________________

1 mg = ____________________

1 pL = ______________________

All physical quantities have dimensions and are expressed in units. Dimension describes ______________________________________________ Units are _______________________________________________________

Example: SpeedSpeed has the dimensions of __________________________________Speed may be measured by a variety of _________________________(e.g. ____________, ___________, etc.)

You can convert between different units of the same _________________________ (e.g. seconds into hours) but CANNOT convert ___________________________________ (e.g you can’t convert time into length)

In the study of mechanics, we will work with physical quantities that can be described in terms of three dimensions:

__________________, ______________________, ____________________

The corresponding basic SI- units are:

Length – 1 meter (1m) is the distance traveled by the light in a vacuum during a time of 1/299,792,458 second.

Mass – 1 kilogram (1 kg) is defined as a mass of a specific platinum-iridium alloy cylinder kept at the International Bureau of Weights and Measures at Sevres, France

Time – 1 second (1s) is defined as 9,192,631,770 times the period of oscillation of radiation from the cesium atom.

ALL physical dimensions can be expressed in terms of combinations of seven ___________________________, which can be measured directly. __________________________ are combinations of 7 basic ones.

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SI Conversions Recopy conversion chart below!

5mL = ________ kL

1st step: What do you expect? Will the number in front of kl be bigger or smaller than 5?

2nd step: Take the given number and multiply it by conversion factors – a fractions where the top and bottom are equivalent – so that you can cross out the units you don’t want and put in the units you need. You will often need multiple steps.

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The wavelength of green light is 500 nm. How many meters is this?

Practice 1: Basic SI conversions

1. How many liters is 16 μℓ ?

2. 4.3 x 104 ns = ___ µs

3. 5.2 x 108 ms = ___ Ks

4. 0.09 cm = ___ pm

5. 906 gigabytes = _____ bytes

More Complex SI conversions

Example 1: Metric to English

20 m/s _______k/h

Example 2: Units raised to a power. **You must raise the conversion factor to the same power as the unit**

7.2 m3 ______ mm3

Practice 2: More complex conversions1. 100 mm3 = ___ m3

2. 60. miles per hour = _____ m/s

3. 75 g/cm3 = __________ kg/m3

4. 9.8 m/s2 = _______ km/hr2

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Must these calculations involve a conversion? What units would the answer have?

a. 30 m + 32 cm + 5 km

b. 60 g + 25 m

c. 18 kg X 35m15 s

Trigonometry & Vectors Guided Notes

Why do we need trigonometry?

Trig allows us to calculate the _______________ or ___________________________________________

We will use trig constantly in the first three quarters of physics … anytime something ____________________________.

Examples:

Finding resultant velocity of a plane that travels first in one direction, then another Calculating the time, path, or velocity of a ball thrown at an angle Predicting the course of a ball after a collision Calculating the strength of attraction between charges in space

etc., etc., etc

Right Triangles

The formulas that we learn today work only with right triangles … but that’s ok, we can create a right triangle to solve any physics problem involving angles!

But, it does beg the question … what’s a right triangle? ________________________________________

Calculating the length of the sides of a right triangle

If you know the length of two of the sides, then use _______________________________________________

Example: A = 3 cm, B = 4 cm, what is C?

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NOTE:

“C” always refers to the ___________________________!

The hypotenuse is always the __________________________ and its always the side that is __________________________________________________.

What if we have one side and one angle? How do we find the other sides?

___________________________________________________________________________

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sin θ = Opposite / Hypotenuse

cos θ = Adjacent / Hypotenuse

tan θ = Opposite / Adjacent

What is SOH CAH TOA?

Calculating the angles of a right triangle

In any triangle (right or not) the angles __________________________.

Example: Find a

In right triangles, we can also find the angle using the _______________________ and _____________ ____________________________

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sin-1 (opp / hyp) = θ cos-1 (adj / hyp) = θtan-1 (opp / adj) = θ

Introduction to Vectors Guided Notes

What is the difference between scalars and vectors?

Scalar Example Magnitude

Speed 20 m/s

Distance 10 m

Age 15 years

Heat 1000 calories

A ___________________ is ANY quantity in physics that has ___________________________, but ______________ ________________________________.

A ___________________ is ANY quantity in physics that has _____________________________ and _______________________________.

How are velocity and speed related?

______________________________________________________________________________________________ ______________________________________________________________________________________________

Example - 20 m/s = ______________ 20 m/s NE = __________________

What is displacement?

_____________________________________________________________________________________________ _____________________________________________________________________________________________

How to draw vectors

The _______________________ of the vector, drawn to scale, indicates the __________________ of the vector quantity.

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Vector Magnitude & Direction

Displacement

5 m, NW

Velocity 20 m/s, N

Acceleration 10 m/s/s, E

Force 5 N, West

The ____________________ of a vector is the ____________________________ of rotation which that vector makes with _________________________or x-axis.

Example: Lady bug displacement

Quick Review

What is the difference between a scalar and a vector? What are the parts of a vector?

Adding Vectors: Plane example 1 – Tailwind

A small plane is heading south at speed of 200 km/h. (This is what the plane is doing relative to the air around it)The plane encounters a tailwind of 80 km/h.

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NOTE 1:

Displacement shows how far apart something is now ________ ____________________________________________. It does not show the path or the total distance travelled.

NOTE 2:

When drawing a vector you MUST MUST MUST ____________ _________________ or arrow on the vector to demonstrate which _________________ it is pointing.

Sketch the problem here!To understand how far the plane is traveling relative to the ground we need to add the two vectors – the plane’s heading and the tailwind.

We add vectors by ____________________ ____________________________and finding the __________________ (sum).

The resulting velocity relative to the ground is 280 km/h S

Adding Vectors: Plane example 2 – Headwind

A small plane is heading south at speed of 200 km/h. (This is what the plane is doing relative to the air around it)It’s Texas: the wind changes direction suddenly 1800. Now the plane encounters a 80 km/h headwind

Adding Vectors: Plane example 3 – Crosswind

A small plane is heading south at speed of 200 km/h. (This is what the plane is doing relative to the air around it)The plane encounters a 80 km/h crosswind going East.

Work the problem here!

The order in which two or more vectors are added _______________________________.

Vectors can be moved around as long as their length (magnitude) and direction are not changed.

Vectors that have the _______________________ and the __________________________ are ________________.

WE DO PROBLEMS

Example: A man walks 54.5 meters east, then 30 meters west. Calculate his displacement relative to where he started.

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Sketch the problem here!How do we figure out the plane’s velocity

relative to the ground?

____________________________________

____________________________________

The resultant vector always goes from the

__________________________________

__________________________________

___________________________________

Sketch the problem here!

Example: A man walks 54.5 meters east, then again 30 meters east. Calculate his displacement relative to where he started.

Example: A man walks 54.5 meters east, then 30 meters north. Calculate his displacement relative to where he started.

You Do Problems

A person walks 5m N then walks 8m S. Calculate his displacement.

A ball is thrown 25 m/s E. A tailwind of 5 m/s E is blowing. Calculate the resulting velocity.

A boat moves with a velocity of 15 m/s, N in a river which flows with a velocity of 8.0 m/s, west. Calculate the boat's resultant velocity with respect to due north

A bear, searching for food wanders 35 meters east then 20 meters north. Frustrated, he wanders another 12 meters west then 6 meters south. Calculate the bear's displacement.

Multiplying a Vector by a Scalar

Multiplying a vector by a scalar will ___________________________________________________________.

The exception: multiplying a vector by a negative number will _______________ its direction.

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Vector Components

Any vector can be “resolved” into two component vectors.

Ax is the horizontal component – or x component -- of the vector.Ay is the vertical component – or the y component – of the vector.

Example A plane heads east, while the wind moves a plane north. As a result, the plane moves with velocity of 34 m/s @ 48°relative to the ground.

Calculate the plane's heading and wind velocity.

What does this mean??It means we need to find the ________________________________________________________________________________________________________________________________________________________________________

Draw the diagram and solve the problem, below.

Example A plane moves with a velocity of 63.5 m/s at 32 degrees South of East. Calculate the plane's horizontal and vertical velocity components.

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Diagram How do we calculate Ax and Ay?

You Do problems

A person walks 450 m @ 120 degrees. Find the x and y component vectors.

A car accelerates 6 m/s2 at 40 degrees. Find the x and y component vectors.

You can reverse the problem and find a vector from its components.

Let:Fx = 4 N Fy = 3 N . Find magnitude and direction of the vector

Diagram and solve the problem below.

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This problem may be written differently, but its exactly the same type of problem we did during our first lesson on vectors!

Just add the components to find the overall vector