3. Q: What is Force? A: Force is anything that causes acceleration. (All accelerations are caused by forces) –Main Principal #4: Objects move, or change motion, because of forces acting upon them! –If an object is stationary, it won’t start moving without a force! –Forces are a “Push” or a “Pull”

4. What we already learned… Makes straight lines on graphs Makes curved lines on graphs

5. So what is the formula for Force? “Newton” (N) is the unit of measurement for Force Q: But what exactly is Mass? Good question! Go to the next slide: So a push could be with a force of (for example) 45 N We have already covered what acceleration is in our last lesson; First we had to know the acceleration formula:

6. Q: So What is Mass? A: Mass is the amount of “Matter” – or “stuff” an object has. –“Stuff” is made up of all of the atoms/molecules that make up the object. We call an objects “resistance to change in movement”: “Inertia” Objects with mass don’t just suddenly start moving by themselves by themselves An object with mass takes some effort to move! If it’s already moving, it takes effort to stop it from moving! Because of the amount of effort It can take to move something, it almost feels like the objects “resists” being moved at all!

7. Think about “Inertia” like this: Again, Inertia is: an objects “resistance to a change” in its current motion. A car is a “heavy” object due to its large amount of mass. It is quite obvious that it is hard to push a car from a stationary position But with enough force (hard enough push) it will move! You have to “overcome” the inertia of the car in order for it to move Man this is heavy! Think: what would be required to move the car if it was a much bigger car? Think: what would be required to move the car if it was a much smaller car? So…the more mass something has, the more force is needed to move it! Ok, trying again, but I will push harder! Ok, that was for getting the object to START moving. But what about stopping when it’s already moving? What if now, a nice heavy car is coming right at YOU? What kind of force would be needed to stop it before it runs you over?

8. Newton’s First Law of Motion: Also know as: Law of Inertia!Also know as: Law of Inertia! –Inertia is an objects resistance to a change in its motion (even if it isn’t moving at all!) –Inertia is caused because objects have mass –The more mass an object has, the more inertia! –“An object at rest will stay at rest unless it is acted upon by an outside force.” (and the opposite is also true! An object in motion will stay in…blah blah blah)

9. What do you think happens to our acceleration w/ different masses? Distance Time Less Mass = less force needed More Mass = more force needed ½ kg 1kg 2kg With less mass, it doesn’t take as much effort to get it moving; therefore, I can move it farther in less time (faster). With more mass, it takes more effort to get it moving; therefore, it takes me more time to move it farther (slower).

10. What do you think happens to our acceleration w/ different masses if we pushed with the same amount of force? Distance Time Which one of these lines do you think would represent a sports car? SUV, Diesel Truck? Sports car would be the steepest line! Steeper = more velocity!!! The Diesel truck would be the least steep line! Less steep = less velocity!!! The SUV would be the middle line! Steepness of line is in the middle = middle velocity