1. Jennifer Brown

2.  What causes forces?: › A force is a push or pull, or an action that has the ability to change motion. › Forces can increase or decrease the speed of a moving object. › Forces can also change the direction in which an object is moving. Jennifer Brown

3. › Forces are created in many ways. › For example, your muscles create force when you swing a baseball bat. Jennifer Brown

4. › Elemental forces:  *Make up all the forces in the universe*  Electromagnetic forces are important to technology.  Gravity is a universal force. Jennifer Brown

5. › The pound is a unit of force commonly used in the United States. › For smaller amounts, pounds are divided into ounces (oz.). › There are 16 ounces in 1 pound. Jennifer Brown

6. › When you measure weight in pounds, you are measuring the force of gravity acting on an object. Jennifer Brown

7. › Although we use pounds all the time in our everyday life, scientists prefer to measure forces in newtons. › The Newton (N) is the metric unit of force.  The Newton is a smaller unit of force than the pound (lb). Jennifer Brown

9.  When solving problems ~  When solving problems ~ Use a force vector Jennifer Brown

10. › The arrow points in the direction of the force. *Remember your coordinate plane* Jennifer Brown

11. › The x- and y- axes show the strength of the force in the x and y directions. › When drawing a force vector to show its strength, you must also choose a scale. Jennifer Brown

12. › One way forces act is the result of direct contact. › A contact force is transmitted by matter directly touching other matter such as wind acting to slow a parachute. Jennifer Brown

13. › The force of gravity between Earth and Moon appears to be what people once called “action at-a- distance”. › Today we know that the gravitational force is carried from the Earth to the Moon by a force field. Jennifer Brown Another way forces act is by  force fields.

14. › Classify These forces as contact forces or the result of force fields: Jennifer Brown

15.  Contact forces from ropes and springs: › Ropes and strings are often used to make and apply forces. › Ropes are used to transfer forces or change their direction. › The pulling force carried by a rope is called tension. › Tension always acts along the direction of the rope. Jennifer Brown

16.  What are the 2 categories of forces?: galaxy M100 about 50 million light years from Earth Jennifer Brown

17. › W = m x g › Weight (N) = mass (kg) x gravity (N/kg) › ~ See Sample Problem › (Pg. 105 in textbook) Jennifer Brown

18. Louise is pushing a basket of apples:  What are two things Louise could change to make it easier to push the basket?  What is one change that would make it harder to push the basket?  Louise could 1. remove some apples 2. get a friend to help 3. push with greater force  Push the basket uphill, add more apples, push over a rough surface Jennifer Brown

19.  http://vimeo.com/4889504 http://vimeo.com/4889504 FORCE Song VIDEO: Jennifer Brown