Introduction to Physics Guided Notesname:______

Introduction to Physics Guided NotesName:______

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?

All physical quantities have dimensions and are expressed in units.

Dimension describes ______

Units are ______

Example: Speed

Speed 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:

______, ______, ______

Thecorresponding 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.

SI ConversionsRecopy 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.

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

Practice 1: Basic SI conversions

How many liters is 16 ℓ ?
4.3 x 104 ns = ___ µs
5.2 x 108 ms = ___ Ks
0.09 cm = ___ pm
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 conversions

100 mm3 = ___ m3

60. miles per hour = _____ m/s

75 g/cm3 = ______kg/m3

9.8 m/s2 = ______km/hr2

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

30 m + 32 cm + 5 km

60 g + 25 m

c. 18 kg X

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?

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

______

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 ______

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.

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.

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.

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.

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.

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.