Unit 2 Force and Transnational Dynamics

I want this website to be your one place to go for resources outside of AP Classroom. Ask me if you should be spending money on books, tutors or websites.

The links are color coded. Fuchsia is required, green is recommended, cyan is challenging and yellow is for extra help.

When you are actually writing something to be turned in, you must be located at least three feet from any other physics student or their work.

Before asking Mr. Skapetis a question, ask each other.

*Hint* If it's underlined, it's a link.

Physics Facts

Lesson 2.1 Systems and Center of Mass

The position of the center of mass for a system can be found using xcm=Σ mx/Σ m
The velocity of the center of mass for a system can be found using vcm=Σ mv/Σ m
The acceleration of the center of mass for a system can be found using acm=Σ ma/Σ m
The center of mass velocity does not change even during collisions.
The motion of a center of mass can only be changed with an unbalanced, external force.
Mass tells how much material is contained in an object.
The units of mass are kilograms.

1) Introduction Activities

Introduction to Acceleration

Velocity as a function of Time Activity

Position as a function of Time

Video Link:

3) Linearizing Data

4) Extra Linearization Practice

Review the video and complete the questions below.

Linearization Practice

4) Practice Problems

Answer as many of these problems as you need. Do not check the solution until you have justified every answer.

Problem Set 1

Calculus Essential Practice

Lesson 2.2 Forces, Free-body Diagrams and Newton's 1st Law

A free-body diagram includes:

1. A labeled arrow representing each force. Each arrow begins on the object and points in the direction in which the force acts.
2. A list of the forces, indicating the agent applying the force and the object experiencing the force.

An object is in equilibrium if it is moving in a straight line at constant speed. (This means acceleration = 0) This includes an object remaining at rest.
When an object is in equilibrium, forces on that object are balanced.
Objects can be in equilibrium in vertical or horizontal directions

A normal force is the force of a surface on an object in contact with that surface.
A normal force acts perpendicular to a surface.
A platform scale reads the normal force.

1) Acceleration Atwood Lab

2) Guided notes.

Playlist

PPT

3) Practice Problems

Problem Set 1...Solution

Problem Set 2....Solution

Answer as many of these problems as you need. Do not check the solutions until you have justified every answer.

4) Relationship Advice

Complete the worksheet, then check the solutions

5) Calculus Connection

Calculus Practice

Focus on the 2nd derivative. This just means you differentiate the function once, then differentiate it again. x(t)'' = a!

Lesson 2.3 Newton's Third Law

Newton’s Third Law says that if object “A” exerts a force on object “B”, then object “B” exerts a force on object “A” with equal magnitude, opposite direction, and of the same type.
A “Third Law Force Pair” is a pair of forces that obeys Newton’s third law.
Two forces in a third law force pair can never act on the same object.
Internal Forces have no affect on an object’s motion

1) Atwood's Machine Lab 1

Instructions for Vernier

2) Guided notes.

Playlist

PPT

3) Practice Problems

1 Set

Problem Set 1...Solutions

Problem Set 2.....Solutions

4) In other Words

Still not getting it? See it explained a different way.

Viren's derivation of kinematic formulas from graphs

Viren's method for solving kinematic problems

5) Calculus Connection

Derivation of kinematics using calculus

Kinematics with Calculus

Practice problems applying derivatives and integrals.

Lesson 2.4 Newton's 2nd Law

For all forces other than the force of the earth, objects must be in contact in order to experience a force. An object’s acceleration is in the direction in which forces are unbalanced.
“Net force” is another name for “unbalanced force.”
The unbalanced force is in the direction of acceleration
Mass attached to a string? use forces!
Newton’s First Law: If ∑F = 0, constant velocity.
F = F so every force can equal another in a given situation Fc = FG, Ff = ma, etc

The two-step problem solving process:
1. Draw a free-body diagram with proper LABELS, LENGTHS, and ANGLES!

1a. If necessary, Break angled forces into components ON A SEPERATE DIAGRAM

2. Write two equations, one for Newton’s second law in each direction:

∑Fx = (stuff that makes it go) – (stuff that holds it back) = max

∑Fy = (stuff that makes it go) – (stuff that holds it back) = may

Weight is the force of a planet acting on an object (Fg = mg).
On earth’s surface, the gravitational field is 10 N/kg. This means that on earth, 1 kg of mass weighs 10 N.
When an object is on an inclined plane, break the object’s weight into components parallel to and perpendicular to the incline. Do not use x and y axes.
1. ∙ The component of the object’s weight parallel to the incline is mgsinθ (this makes the object slide, NOT “gravity”)
2. ∙ The component of the object’s weight perpendicular to the incline is mgcosθ
This is usually FN, so Ff = μmgcosθ

1) Guided notes.

Playlist

PPT

2) Practice Problems

1 Set

Problem Set 1

Problem Set 1 Solutions

The solutions are restricted, so please ask Mr. Skapetis to view them

Lesson 2.5 Kinetic and Static Friction

The force of friction is the force of a surface on an object acting along the surface. The force of friction acts in the opposite direction of an object that is sliding.
Traction (static friction) helps an object to move
The coefficient of friction μ is not a force.
The coefficient of friction is a number that tells how sticky two surfaces are
The force of friction is equal to the coefficient of friction times the normal force Ff = μFn
The coefficient of kinetic friction is used when an object is sliding; the coefficient of static friction is used when an object is not sliding. Both types of coefficients of friction obey the same equation.
The coefficient of static friction can take on any value up to a maximum, which depends on the properties of the materials in contact.
For two specific surfaces in contact, the maximum coefficient of static friction is greater than the coefficient of kinetic friction.
F = F, so friction can be the centripetal force if that is the only force acting Ff = mv2r = μFn like in a turning car
On an inclined plane, Ff = μFn = μmgcosΘ
1. If constant velocity on an inclined plane, μ = tanΘ

3) Misconception Acknowledgment

Read the section on the website.

4) Practice Problems

Problem Set 1 Solutions

Problem Set 2

Problem Set 3

5) Recommended Videos

Penny from the Empire State Building

Flipping Physics

Prince Rupert's Drop

Lesson 2.6 Spring Forces

A spring pulls with more force the farther the string is stretched or compressed.
The force of a spring is given by the equation F = kx. Here, k is the spring constant of the spring, and x is the distance the spring is stretched or compressed. The negative sign is a directional indicator for the displacement
The spring constant is a property of a spring, and is always the same for the same spring. The standard units of the spring constant are N/m.

1) Mu of the Shoe

Complete the activity with 2 other partners.

2) Guided notes.

Playlist

PPT

3) Practice Problems

Problem Set 1......Solutions

Complete all Problems

Problem Set 2

Problem on first page, answer on following page

Problem Set 3

4) Mr. Skapetis' Favorite Youtube Playlist

Well one of them, for sure. Watch the lesson 3 video in its entirety. If there is any experiment you wish to see, ask me in class.

5) IRL

Physics could save your life

Why is ice slippery?

6) Extra Lab Practice

(or absence substitution)

Complete this lab sheet using this site.

Lesson 2.7 Circular Motion

An object moving at constant speed v in a circle of radius r has an acceleration of magnitude v2/r
Acceleration/force is always directed toward the center of the circle.
Even though the speed is constant, the direction is changing so there is acceleration

Momentum in a direction is conserved when no net external force acts in that direction.

Lesson 2.8 Gravitational Force

All massive objects attract each other with a gravitational force.
The gravitational force FG of one object on another is given by

∙ M is the mass of an object

∙ d is the distance between the centers of the two objects

∙ G is the universal gravitation constant, 6.7 x 10-11 N·m2/kg2

The gravitational field g near an object of mass M is given by g = Gm/r^2

where d represents the distance from the object’s center to anywhere you’re considering.

The weight of an object near a planet is given by mg, where g is the gravitational field due to the planet at the object’s location.
The gravitational field near a planet is always equal to the free-fall acceleration.

Gravitational mass is measured by measuring an object’s weight using weight = mg
Inertial mass is measured by measuring the net force on an object, measuring the object’s acceleration, and using Fnet = ma.
In all experiments ever performed, gravitational mass is equal to inertial mass.
To find the speed of a circular orbit, set gravitational force equal to ma, with .
1. Orbital velocity is the tangential speed of an orbiting body vorb = GMpr (M is mass of planet)

Unit 2 Practice Test

Physics Facts

Practice Test FRQs .......................FRQ Solutions

Google Sites

Report abuse