What is a force? Force- a push or a pull. When you push on something or pull on something, you are using a force. With the person next to you, write down one sentence for each person describing how you used a force getting ready for school this morning. You must use the word force in your sentence. This boy is using a force to pick up his cat. He is pulling his cat up from the ground.

Forces are measured in a unit called Newtons (N). Named after Sir Isaac Newton It’s about as much force as you picking up an apple against the force of gravity. 1N Forces always exist in pairs. This means when you push on something it pushes back. You can’t touch something without it touching you back. This girl is pushing on the books, but they are pushing on her hands, too

FORCES HAVE TWO PARTS A FORCE HAS AN AMOUNT AND A DIRECTION. A FORCE HAS AN AMOUNT AND A DIRECTION. WHY DO YOU THINK A FORCE NEEDS A DIRECTION WITH IT? WHY DO YOU THINK A FORCE NEEDS A DIRECTION WITH IT? (Why does direction matter?) (Why does amount matter?)

Combining Forces Usually there is more than one force affecting an object. When forces are in the same direction, you add them together. Look at page 376. They are pushing the box together so it is going to the right with a force of 300 N. When forces are in the opposite direction, you subtract. The larger force wins the direction! Look at page 376 again (middle picture). The people are pushing the piano but in different directions. Of course the guy is pushing harder…so the overall movement is to the right. The difference between the two is 100N to the right. The force left over is the NET FORCE Net force is the overall force on an object when all the individual forces acting on it are added together

NOW YOU TRY!!! With your partner, discuss each picture. Use the words force, net force Newtons in your group discussions. For each example, write down the NET FORCE and the direction the object will move. 1.Boulder ________ 2.Swing _________ 3.Guy with GOLD! __________

Now You Try! 6N 5N 25 N 40 N 25 N 4 N 30 N Boulder Swing Guy with GOLD!