1. Applied Science III- Finau

2. What causes motion? For example, what causes a book to slide across a table? Or a flag moving up a flagpole?  A push?  A pull?  A force!

3. What types of forces are there?  Contact Force  Push or pull – something touching something else  Field Force  Gravity  Electromagnetic  Strong & weak nuclear forces – think bonds in chemistry

4. What is Newton’s 1 st Law of Motion?  An object in motion (or at rest) tends to stay in motion (or at rest) unless acted upon by a Net force  Also known as the “Law of Inertia”

5. What is inertia?  An object’s resistance to a change in motion  Depends on the amount of mass an object has

6. What is matter?  All of the atoms and molecules that make up everything  Everything in the universe is made up of Matter

7. What is mass? Is it different from weight? Does mass affect weight?  Mass is a numerical value for matter  Matter and weight are different  Weight depends on gravity; Mass does not  The more mass, the more weight

8. What does weight depend on?  Weight depends on the mass & the gravity acting on the object

9. Is there a difference between mass and volume?  Which weighs more…a ton of feathers or a ton of bricks?  Both the same…but which has more volume?  The feathers – you would need many more feathers to equal the same weight in bricks  Mass & Volume are independent

10. What is density?  What floats better…an inflatable raft or a lead bar? Why?  The lead bar has more mass in its volume than a raft – it’s more Dense  Density – the amount of mass per volume

11. What has more inertia: A bus standing still A dude on a bike riding 10 mph  Think about which one is harder to change its motion  The bus has more inertia – because it has more mass

12. What is equilibrium?  When all of the forces acting on an object are balanced – equal and opposite  No change in motion!

13. If I have force, do I have movement?  Not always – forces acting in opposite directions can cancel each other out.  Example – try pushing on a wall of a building

14. What is Net Force?  A force that is not in equilibrium – causes a change in motion  Kind of like saying “Total Force”

15. What has more inertia and why? -A Boeing 747 sitting still on a runway -You driving in a Delorean at 20 mph  The Boeing 747 because it has much more mass  Speed of an object does not affect inertia

16. Which has the most inertia? Why? -You -A banana tossed across the room -An elephant running in the wild -A mustang speeding down the road at 115 mph -A skyscraper  A skyscraper because it has much more mass

17. What has more weight? which has a higher density? -A ton of feathers -A ton of bricks  Both weigh “a ton” – same weight  The bricks are much more dense

18. Which are in Equilibrium and why? -A car sitting at a stop sign -A car accelerating from 0 to 60 mph -A car driving straight at a constant 60 mph -A car driving in a circle at a constant 60 mph  Sitting at a stop sign – movement does not change  Driving straight at a constant 60 mph – movement does not change

19. What does a Force cause an object with mass to do?  Change its motion – ie. Accelerate!

20. What happens to the acceleration of an object if I increase the force with which I push? What’s the relationship between force and acceleration?  If you push harder – object moves faster  As force increases, acceleration increases  As force decreases, acceleration decreases  Force & Acceleration are directly proportional

21. What happens if I keep my force the same but my mass increases? What is the relationship between mass and acceleration?  If you push a heavier object, it won’t move as much  As mass increases, acceleration decreases  As mass decreases, acceleration increases  Mass & Acceleration are Inversely Proportional

22. Using our relationships above, what is an equation to find acceleration of an object?  Create equation together…  As force increases, acceleration increases F A  As mass increases, acceleration decreases M A a = F X m

23. What is Newton’s Second Law of Motion?  Acceleration is directly proportional to the Force, but inversely proportional to the Mass of an object  F = ma  Units for Force – Newtons (N)

24. A little math…how much Force does it require to cause a 50 kg object to accelerate at 3 m/s 2 ?  m = 50 kg  a = 3 m/s 2  F = ma  F = 50 X 3 = 150 N

25. A little more math…how much mass does an object have if it accelerates at 5 m/s 2 when I apply a 500 N force?  a = 5 m/s 2  F = 500 N  F = ma  m = F/a  m = 500/5 = 100 kg

26. Last bit of math…how much does a 50 kg object accelerate if a 200 N force is applied to it?  m = 50 kg  F = 200 N  F = ma  a = F/m  a = 200/50 = 4 m/s 2

27. What is pressure? If I apply the same amount of force, can the pressure change?  Pressure is the amount of force applied to an area  Pressure can increase if you apply the same force in a smaller area  What hurts more – poked by an eraser or poked with a pencil tip?

28. How do I find pressure?  Pressure depends on Force & Area  Pressure = Force/Area

29. Does a stick of dynamite have Force?  The dynamite does NOT have force itself  Does have energy stored inside  When it explodes, it can apply a force to the objects around it

30. A car accelerates from 0 to 60 mph in 5 seconds. Strictly speaking, what exactly is the force that is accelerating the car? (how is the car moving forward?)  The road pushing back on the car  If the road was frictionless, the car could not move  Thus, the engine only indirectly propels the car forward

31. Can a single force act by itself? Why?  No, all forces are created in pairs  When you punch something, you apply a force  You feel pain because a force is applied back to you

32. What’s Newton’s 3 rd Law of Motion?  For every force, there is an equal and opposite force created

33. Can you name a couple of examples of Newton’s 3 rd Law?  Examples…

34. When walking across the floor, why do you move? Is it easier to walk on carpet or a sheet of ice?  Your foot pushes backwards on the floor; the floor thus pushes back on you to propel you forward  Ice does not have enough friction to help push you along as easily

35. A cannon on a pirate ship fires at another ship. If the cannon doesn’t move back much when fired, why does a cannon ball get fired so fast?  The cannon weighs much more than the cannon ball  the forces acting on each are the same, but is able to move the cannon ball more because it has less mass