Chapter 12 Force

Force Vocabulary FORCE- BALANCED FORCES- UNBALANCED FORCES- A push or pull. Forces that are equal in size, but opposite in direction. Forces that cause a change in the motion of an object.

GRAVITY- Force of attraction between all objects in the universe. NEWTON- WEIGHT- MASS- SI unit of force. The amount of matter in an object. Measure of the force of gravity acting on an object.

FRICTION- STATIC FRICTION- SLIDING FRICTION- ROLLING FRICTION- AIR RESISTANCE- Force that opposes the motion of an object. Occurs when objects are not moving. Occurs when 2 objects slide past each other. Occurs when 2 objects roll past each other. An upward push as an object falls.

LUBRICANTS- Materials that reduce friction.

Key Topic is… What is Force? Our Objective is… Define force and give examples of forces in nature. Identify balanced and unbalanced forces and describe their effects.

1st Main Idea… Force  A ________ is _________________________.  A ______ always ___________________________.  If the force is _________ __________, the object _____ ______ in the ________________________.

Force ? ? PUSH PULL Courtesy: Clipart.com Courtesy:tugfest.com

Ch. 12 Force Sec nd Main Idea… Balanced Forces  To _______ a force, you must ________________.  1.  2. ______ forces are _____________________ and ______________________. _________ forces do not

Examples!! Balanced Forces-No Movement 25 N Courtesy: clipart.com

Force 3rd Main Idea… Unbalanced Forces  _________ forces cause ___________________ ____________________.

Ch. 12 Force Sec 12-1 UnBalanced Forces-Movement 25 N 10 N Courtesy: clipart.com

Force 4th Main Idea… Forces & Motion  ________ forces can ______________ _______________________.  1.  2.

5th Main Idea… Forces In Nature Examples of forces you experience everyday:  _________- a measure of _________ between ________________________.  _______ force- attraction of a __________________________________.  _____ force-moving _________________.  Falling ______ is caused by ________________.

Force

Force – Part 2 Key Topic is… What is Gravity? Our Objective is… Explain Newton’s laws of gravity.

Force – Part 2 1st Main Idea… Sir Isaac Newton  ________ hypothesized that there is a ________ called _________ that makes _________________________________ ______.  Newton’s law of Universal Gravitation- _________________________________ _________________________________ _________________________________.

Ch. 12 Force Sec nd Main Idea… Gravity  _______ is a _____________________ between ________________________.  ____ _________ on or near _________________ are ________ toward __________________________ _________________________________.

Force – Part 2 3rd Main Idea… Gravity & Mass  The amount of ____________________ between ____ _________ depends on ____________________________________ ________.  When an apple falls, they both _________________________________.  However, because___________________ than the ______, the Earth_____________.

Force – Part 2 4th Main Idea… Gravity & Distance  The ____________________________ between _________________________ as the __________________________.

Force – Part 2

Forces – Part 2 1. DESCRIBE: In which direction does an object fall on Earth? 2. EXPLAIN: Why is the force of Earth’s gravity so strong?

Force – Part 3 Key Topic is… How does a Spring Scale Work? Our Objective is… Describe how a spring scale is used to measure weight.

Force – Part 3 1st Main Idea… The SI Unit of Force  The _______ is the ________________.  On Earth, ________________________ to lift a __________________________.  ________ is a measure of the _________________________________.  Because it is a ______, the object’s ________ is measured in _________(N).

Force Part 3 2nd Main Idea… Using a Spring Scale  A ________ ________ measures the _________________________________ ____________; this is also called its _________________.

Force – Part 3 3rd Main Idea… Types of Spring Scales  There are ______ _____ of _______ _________. Ex. Lab scales, bathroom scales & market scales.  Weight pushes or pulls on a _______ causing a dial or pointer to turn until it shows the _______ of the object.

Ch. 12 Force Sec 12-3

Force – Part 3 1. IDENTIFY: What are you measuring when you weigh an object? 2. IDENTIFY: What does a spring scale measure? 3. What are three types of spring scales?

Force – Part 4 Key Topic is… What is Friction? Our Objective is… Identify examples of friction.

Ch. 12 Force Sec st Main Idea… Forces & Motion  To stop a _______ ________, a _______ must act in the __________________to the direction of the __________.  Observe: Give your book a slight push. What happens? __________________.  What must you do to keep it moving? ________________________________.

Force – Part phys.uaf.edu/211_fall2002.web.dir/Ben_Towns end/StaticandKineticFriction.htm champions.com/science/friction.htm

Ch. 12 Force Sec nd Main Idea… Friction _______ is a_______________________ ____________________________.

Force – Part 4 3rd Main Idea… Types of Friction Types of friction when there is contact between surfaces:  _______ friction, a book ____________.  ______ friction, a book _____________.  ______ friction, contact between bike ________.  ___ __________ (Fluid friction) pushes _______ _______________ as it falls.

Force – Part 4

4th Main Idea… Useful Friction  _______ makes ___________________.  Without ___________, you would not be able to ___________________, _______________, _________________, or ___________________.

Force – Part 4 5th Main Idea… Harmful Friction  Unwanted _________ can be found in ________ ___________________.  _______ _____ rub together and ______ ______ and can cause __________________________.

Ch. 12 Force Sec 12-4

Force – Part 5 Key Topic is… How can friction be changed? Our Objective is… Describe some ways to change friction.

Force – Part 5 1st Main Idea… Moving Against Friction  Because friction _______________________ to move _______, ______________ is needed to _________________________________.

Ch. 12 Force Sec nd Main Idea… Using Rolling Friction  One way to _______ ________ is to __________ ________ ________ to _____________________.  _______ friction is ________________________ friction.

Force – Part 5 3rd Main Idea… Using Lubricants  __________ are ___________________.  ____ is a ____________ that ________ ________________________ from one another.

Force – Part 5 4th Main Idea… Not Enough Friction  Slipping on an icy sidewalk or a ____________ _____________ are examples of when there is _______________________________ surfaces.  To ________ ________ we sometimes _______ _______ on an _____ _____ or wear special __________________.

Force – Part 5

Force – Part 5 1. CALCULATE: If the force of friction is 16 N, how much force is needed to move the object? 2. IDENTIFY: When would it be helpful to use a lubricant? 3. HYPOTHESIZE: Why do staircases often have rubber mats on the steps?