Opener

Opener

PICK UP A NOTE PACKET FROM THE SIDE COUNTER

Describe a force (what does it do? What is it?)

CHAPTER 4Newton’s 1st Law of Motion

Today I will:• Define and distinguish between mass,

weight and volume• Solve for mass and weight

What is mass?

Mass – the amount and type of material present

a measurement of inertia; the more mass an object has the more inertia it has

Scalar quantitySI units kilogram

Scientific definitions:

Mass – the quantity of matter in an object; a measure of the inertia, or “laziness,” that an object exhibits in response to any effort made to start it, stop it, or otherwise change its state of motion

How are mass and volume different?

Mass – the amount and type of material present

Volume – measure of space and is measured in units such as cubic centimeters, cubic meters, and liters

Object may have a large mass but not a large volume

Example: Take two bags of the same volume, fill one with feathers and one with rocks, do they have the same mass….

• NO

Mass is NOT weight!

How are mass and weight different?

Mass is the amount and type of material present

Weight is a measure of the gravitational force acting on the object and depends on the objects location.

Weight – the force of gravity on an objectIt is a vector quantity

Weight is a force F = ma …..so = m

SI units: Newton (N) which is kg*m/s2

1 kg = 2.2 lbs

Find you weight in Newtons!

X = your mass (kg)

= m = m (-9.8 )

Mass and WeightWhile they are not the same; they are directly proportional to each other

Objects with great mass have great weight;

objects with little mass have little weight

Today I will:

Define forceIdentify the

different types of forces

Mass and weight: Which one is universal and why?

Vocab…

Force – any push or pull

Force

A force is a push or pull. An object at rest needs a force to get it moving; a moving object needs a force to change its velocity.

The magnitude of a force can be measured using a spring scale.

Forces…

What is a force?Any push or pull on an object

Forces are vector quantities

Types of Forces

Weight – force of gravity on an object; acts directly downward

Support or Normal force – force acting upward on an object opposing gravity; acts perpendicular to the surface

Tension – name given to the force on ropes, strings or chains

Types of Forces con’t

Friction – force between materials that touch as they move past each othercaused by irregularities in the surface

When friction is present, some force is required to keep an object moving

Acts in a direction that opposes the objects motion

Galileo Con’t

Inertia – objects resistance to change of motion

Today I will: Opener:

Explain balanced and unbalanced forces

Define equilibrium and net force

Explain the relationship between net force and motion

Name the 4 types of forces and describe each

Balanced vs Unbalance forces

Balanced Forces = all forces acting on the object cancel each other out

Unbalanced Forces (external) = the forces acting on an object do not cancel out; there is a resulting force

When forces are balanced:

Objects at rest: will remain at rest (a balanced force acting on them)

Objects in motion: will keep moving with a constant velocity

When forces are Unbalanced:

Objects at rest: will move when an unbalanced force acts on them

Objects in motion: moving at a constant velocity will accelerate

To get the object to move you must apply a force!!

Vocab

Net force - the combination of all forces acting on an object(Net force is the resultant force or the sum of all forces)

Add up all the forces in the x and y direction

Equilibrium – occurs when all the forces add up to zero (so the net force is zero); there are forces acting on the object but they all cancel outMeans objects have a balanced

force acting on them (so they are at rest or they are moving with a constant velocity)

What does it mean to say that forces are unbalanced or external?

The net force is not zero!

Two Categories of Net force

Net force = 0Object is in equilibriumObject is not moving or moving at a constant velocity

Acceleration = 0Net force ≠ 0

Object is accelerating

CDP (blue packet)

Back of 4-1 (4-6)Front of 4-2Back of 4-3(rest of packet we will do later)

Today I will: Opener:

Determine tension in ropes that are at placed at angles

Explain Newton’s First Law of Motion and how it relates to motion and inertia

Give an example of Newton’s First Law in action

Explain what it means to have a net force of zero.

Have out CDP

1.DEFINE NET FORCE 2.HOW DOES NET FORCE RELATE TO MOTION OF THE OBJECT

Concept Check

Go over homework: CDP (blue packet)

Back of 4-1 (4-6)Front of 4-2Back of 4-3(rest of packet we will do later)

What happens if the ropes are not straight up and down but are out at an angle?

Back of CDP 4-2 and front of 4-3

Historical Figures

Aristotle (384 – 322 BC)2 categories of motion

natural motion – straight up or straight down; didn’t think there was a reason …just thought that is what objects do….objects just fall

Violent motion – imposed motion; result of forces pushing or pulling

Thought that the Earth was the center of everything.

Copernicus (Nicolaus Copernicus February 19, 1473 – May 24, 1543)Earth and other planets move around

the sunBook published on day of his death

Homework:

Bookwork found on pages 56-58 all plug-n-chug

Galileo – (Galileo Galilei February 15, 1564 – January 8, 1642)Big supporter of Copernicus

Believed in the theory of the sun centered universe

Studied under house arrestStudied the fact that objects all fall at the same rate (sentenced in 1633 – was in his sixties)

Galileo – (Galileo Galilei February 15, 1564 – January 8, 1642)

Galileo looked at how things worked rather than why

Known as the “father of modern day physics”

How did the incline work?

Incline planes…

Turn to page 45 in book….Refer to pictures for information

Galileo and Kepler

Letters recorded as early as 1597 (Galileo in early thirties)

Excerpt from letter to Kepler: August of 1610

My dear Kepler, I wish that we might laugh at the remarkable stupidity of the common herd. What do you have to say about the principal philosophers of this academy who are filled with the stubbornness of an asp and do not want to look at either the planets, the moon or the telescope, even though I have freely and deliberately offered them the opportunity a thousand times? Truly, just as the asp stops its ears, so do these philosophers shut their eyes to the light of truth."

Complete bookwork: all think and solve

Isaac Newton January 4, 1643 – March 31, 1727

Newton’s Law of Inertia also called Newton’s First LawEvery object continues in a state of rest, or of motion in a straight line at constant speed, unless it is compelled to change that state by unbalanced forces exerted upon it.

NOTE: Saying in a straight line at a constant speed is the same thing as saying CONSTANT VELOCITY! This means the object is NOT accelerating

Newton’s First Law - video

Punching and Newton’s First Law

Demonstrations

HammerCup and penny

Friction

Check point questionsSitting at a stop light, you get hit by a car from behind.

Which way do you move? (not the car…you!)

You have a pair of sunglasses sitting in the center of the dashboard, you make a sharp left hand turn which way do the glasses move?

Opening Question:

Today I will:

What is Newton’s First Law of Motion?

Review Newton’s First Law

Define net force and equilibrium

Find the net force on an object

Newton’s First Law Video

Tablecloth

In Newton’s First Law it says an object will keep doing what it is doing unless acted on by unbalanced forces

Unbalanced means acted on by a net force

Complete CDP 4-1 front and 7 on the back and NTQ (all)

Today I will: HW: work on lab

Explain equilibrium and find the net force acting on the ring on the force table

Review Ch 4 Concepts

HW for Friday: page 56 RQ 14-20; TE 31-37; TS - 38-39; CDP Chapter 4

Number 6

#7

Draw the three vectors to scale TIP TO TAIL (ALL THREE CONNECT)

Then draw each by itself to then find the E/W N/S (X and Y components)

#8

Add up the X’s to get a total; add up the Y’s to get a total in each direction

Compare those to the resultant from what you drew in for the fist part of #7

HW:

Entire blue CDP packet

HW for Friday: page 56 RQ ALL, ALL TE, all pc and all from page 667