DO NOW A baseball and a tennis ball are dropped from the same height. Which has more mass? Which has more weight? Which hits the ground first?

Reminders Interim Report Cards due Wednesday Missing Work? Ch. 10 Test Corrections? Ch. 11 Test Review on Wednesday Ch. 11 Test on Friday michaelpaciplp.weebly.com Media Release Form (Science Bucks!)

Agenda for Monday, March 9, 2015 TOPIC: Free Fall & Momentum Essential Questions: How does gravity and air resistance impact falling objects? What is momentum and how is it conserved during collisions?

Agenda for Monday, March 9, 2015 Agenda: Notes on Free Fall Video Demos Notes on Momentum Video Demos Newton’s Cradle Demo Momentum Word Problems

Today’s Objectives Students will be able to: Explain the effect of gravity and air resistance on falling objects Explain why objects in orbit are in free fall Calculate the momentum of moving objects

Gravity and Motion

Galileo Galilei – late 1500’s Dropped 2 Cannonballs of different masses from the Leaning Tower of Pisa to prove that mass does not affect fall time

Gravity and Acceleration Acceleration due to gravity is g=9.8 m/s 2 for all objects on Earth Velocity of a falling object Velocity = g (acceleration due to gravity) * time

Air Resistance & Falling Objects Force that opposes the motion of objects through the air

Terminal Velocity Occurs when downward force of gravity is equaled by upward force of air resistance. Falling object stops speeding up and falls at the same rate.

Penny Dropped from Empire State Building Myth or Fact? If you dropped a penny from the empire state building, could it kill someone? Penny Drop

“Free Fall” When gravity is pulling down on an object and no other forces are acting upon the object Gravity in a Vacuum

Orbiting When one object orbits another in space Spacecraft move forward but are also in free fall, causing orbit How do rockets get into orbit? Cannon Shell Orbit

Projectile Motion Curved path an object follows when projected near the surface of the Earth

MOMENTUM

What is Momentum? The product of the mass and velocity of an object. momentum Which moving vehicle do you think has greater momentum?

Calculating Momentum Equation: p = m x v p = momentum m = mass (kg) v = velocity (m/s) Momentum always has the same direction as the object’s velocity.

Math Focus What is the momentum of an ostrich with a mass of 100 kg that runs with a velocity of 6 m/s north? p=m*v p=100 kg * 6 m/s north p= 600 kg*m/s north

Law of Conservation of Momentum When two objects collide, the total amount of momentum stays the same. Momentum before a collision is equal to momentum after collision Example : Playing Pool

Law of Conservation of Momentum One of two things happen when objects collide: 1. Objects will stick together and move as one object. (ex - football tackle) Masses of both objects are added together and both objects have a new velocity

Law of Conservation of Momentum 2. Objects will bounce off each other and momentum is transferred from one object to the other (ex – billiard (pool) balls) Objects move at different directions and at different speeds.

Movie Momentum and Football

Conservation of Momentum & Newton’s Third Law For every action, there is an equal and opposite reaction. Action & Reaction forces are equal and opposite - momentum is neither gained nor lost. Ex: Newton’s Cradle!

Guided Practice: Example Problem 2. What is the momentum of a child and wagon if the total mass of the child and wagon is 22kg and the velocity is 1.5m/s?

Guided Practice: Example Problem 7. A 25 gram bullet is fired from a gun with a speed of 230m/s. If the gun has a mass of.9kg. What is the recoil speed of the gun?