What to do… Open your notes to page 36 Answer the following question in the “Think About It” Have you ever heard someone say “What goes up, must come down!”? What does that mean. Do you have any examples?

A quick Review Tell your partner Newton’s 1st and 2nd Laws

Newton’s 1st Law An object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted upon by an unbalanced force.

Newton’s 2nd Law of Motion The acceleration of an object is equal to the net force exerted on the object divided by the object’s mass. Force = Acceleration = The acceleration due to gravity on earth = Mass x Acceleration Force Mass 9.8 m/s2

Newton’s Third Law Chapter 20, Section 2 SPI: 11.4- Identify and explain how Newton’s laws of motion relate to the movement of objects.

Newton’s Third Law of Motion If one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object “For every action there is an equal but opposite reaction”

Action – Reaction Pairs Examples Gymnast pushes down on vaulting horse, the horse pushes him up and over Kayak paddle pushes the water back, the water pushes the kayak forward A dog pushes down on the ground, the ground pushes up on the dog causing it to leap into the air Other Examples…?….

Detecting Motion You can’t always detect motion when paired forces are in action. If one of the pairs is more massive, you will only see the less massive object move Example – When you push down on the Earth, you won’t see the Earth move, only you jumping in the air

Do Action – Reaction Forces Cancel? If 2 equal actions act in opposite directions they are balanced and cancel each other out. There is no movement Action – Reaction forces do not cancel out because they are acting on 2 different objects

Momentum *A characteristic of a moving object that is related to the mass and velocity of the object. *Momentum = mass(kg) X Velocity(m/s) *Like velocity and acceleration, momentum has a direction. Its direction is the same as its velocity

Momentum More momentum = harder to stop More mass = more momentum. You can stop a baseball traveling 20m/s, but not a truck The greater the velocity an object has, the harder it is to stop. An arrow shot from a bow has a large momentum even though it has a small mass

Conservation of Momentum Conservation – same amount before and after an event Total amount of momentum objects have when they collide is conserved Law of Conservation of Momentum – states that in the absence of outside forces, the total momentum of objects that interact do not change

DO!! Hot gas is produced through the combustion of a fuel. The hot exhaust gas flows through the rocket nozzle. The rocket is able to launch off the ground.

Keys to Understanding At LEAST 5 complete sentences Summarize the main points of the lesson Describe in detail the important ideas Write about concepts you want to remember This should be helpful to YOU!

Test Friday! Complete the Physics Study Guide Part 2 by Wednesday 9/14