Chapter 14

 Watch your teacher perform the Egg Drop demonstration.  Predict: What will happen to the egg if a force caused the pan to suddenly move?  Think about this:  What forces are acting on the objects before, during, and after the demonstration.  What happened to the egg and why do you think this was the outcome?

 A force is a push or pull; things move when they are acted on by a force.  Often, more than one force acts on an object at the same time. The total of all the force on the object is called the net force.  When forces act against each other with equal strength in opposite directions, the net force is ZERO and the object will not move.  When one force is greater than the other the net force is NOT ZERO and the object will move.

F = 20 N East F = 20 N West F = 18 N East F = 20 N West

 In science, any change in an object’s motion is called acceleration.  Refers to an object’s  Increasing speed  Decreasing speed  Changing direction  Changing speed and direction

 Sir Isaac Newton was an English scientist in the late 1600’s who proposed three laws of motion.  Newton’s three laws of motion explain how inertia, an object’s mass, acceleration, and the forces acting on the object are related.

 Objects at rest will remain at rest unless acted on by a nonzero net force.  Objects moving at a constant speed and direction (velocity) will continue moving at that rate unless a nonzero acts on it.  The tendency of an object to resist a change in motion is called inertia.  ere/Newton/law1.html ere/Newton/law1.html

 If you kick a soccer ball, and no one stops it, why does it eventually slow and stop?  Friction and gravity are forces that act against it  How can I make the soccer ball go further?  Reduce the friction (on concrete or ice vs grass) or increase the force that you kick with (kick it harder)  If I roll a soccer ball and a bowling ball with the same force on the street, which one would be harder to stop?  The bowling ball because it has more mass and it’s inertia is greater

 Think about what happens to the pipes when you drop the cup. What causes this to occur?  Try This: Put the penny on your elbow then try to catch the penny with the same hand. How is this possible? Can you explained this using Newton’s 1 st Law of Motion?

 An object’s acceleration depends on its mass (the amount of matter in an object) and the net force acting on it.  The mathematical equation for this law is:  Force (F) = Mass (M) x Acceleration (A) Or:  Acceleration (A) = Force (F) / Mass (M)  ere/Newton/law2.html ere/Newton/law2.html

 On a swing, who would require more force to push? Why? Jonathan Vilma: or Steve Urkel 6’11” / 230 lbs5’6” / 110 lbs

 On a swing, if you applied the same force to each person, who would have the greatest acceleration? Why?  Jonathan Vilma: or Steve Urkel  6’11” / 230 lbs5’6” / 110 lbs

 Using your left pinky finger, try to push the paperback book across the table.  Using the same finger, try to push the hardback book across the table.  Which required more force? Why?  Can you explain this using Newton’s 2 nd Law of Motion?

 If one object exerts a force on another object, then the second objects exerts a force of equal strength in the opposite direction.  “For every action there is an equal and opposite reaction.”  ere/Newton/law3.html ere/Newton/law3.html

 What happens when you blow up a balloon, then let it go (without tying then open end)?  Why does this happen (using Newton’s 3 rd Law of Motion)?

 Watch what happens when you drop the basketball and tennis balls separately.  Watch what happens when you drop the basketball and tennis balls together.  What’s the difference between the two drops?  Why do you think this happened? Explain this using Newton’s 3 rd Law of Motion.

 Make a fork and spoon magically “levitate” on the glass using the provided materials.  Think about this: Which of Newton’s Laws are you using to complete this “magic trick”?

 The force that pulls an apple to the ground also pulls satellites (including the moon and International Space Station) toward Earth, keeping them in orbit.  Gravity attracts all objects toward one another.  Newton’s Law of Universal Gravitation states that every object in the universe attracts every other object.

 The strength of the force of gravity between two objects depends on two factors:  The mass of the objects  The distance between the objects

 Mass is the amount of matter in an object  Earth is extremely massive and therefore exerts more force than you  The force of gravity decreases as the distance increases  The further an object, the less gravity is exerted on the object

 The measure of the force of gravity on an object is called weight.  If you go to the moon, what would change, your mass or your weight?  Your WEIGHT would change depending on your location (like the moon) because the gravity is different there (1/6 th as much)  Why is gravity different on the moon than on Earth?  The moon has less mass than Earth, so it also has less gravitational pull.

 Recall Newton’s 3 Laws of Motion and think about which one may explain this:  What keeps objects orbiting Earth (like the moon, satellites, or the International Space Station)?  Newton concluded that inertia (1 st Law of Motion) and gravity keep Erath in orbit around the sun, and the moon and ISS in orbit around Earth.

 You will be working on a group project creating a game that can be played on the International Space Station.  To do this, you will be putting to use the information we learned about forces, Newton’s Laws of Motion, and gravity.

 How are things different in space than they are here?  How do objects move differently in space?  If I hit an object in space, with micro-gravity, what would happen to that object?