Sir Isaac Newton

Legend Newton made a connection between why objects fall to the earth and what keeps the objects moving when he watched an apple fall –Unbalanced force caused the apple to fall down on earth –Unbalanced force on the moon kept the moon moving in a circular motion –Force of attraction--gravity

Review Force What is force? –A force is a push or a pull.

Video Time St. Mary’s Physics: First Law

Sir Isaac Newton –1 st Law – an object at rest or in motion stays at rest or in motion unless acted upon by an outside force * Known as the “Principle of Inertia” –2 nd Law – describes how an object accelerates or changes direction when a force is applied to it * F = ma –3 rd Law – for action there is an equal and opposite reaction

Newton’s 1 st Law of Motion An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force. (outside force)unless acted upon by an unbalanced force The velocity of an object remains constant unless acted on by an unbalanced force. “Law of Inertia”

Newton’s 1 st Law of Motion

Inertia - the resistance an object has to a change in its state of motion. [Newton’s 1st Law]Inertia Equilibrium - if the net force on an object is zero, then it is said to be in equilibrium. –An object is in equilibrium when: at rest or moving at constant velocity.

Examples of equilibrium Equilibrium - resultant = 0 N Example 1

Examples of Equilibrium Velocity is Constant (rest or constant v)

Wacky Pennies What is Newton’s First Law? Purpose: Does the mass of an object effect the inertia.

Wacky Pennies Procedures: –1. Stack 4 pennies on your table. –2. Aim one penny at the bottom of the stack of 4 and flick with your finger. –3. Make observations on a separate sheet of paper. –4. Flick a stack of 2 pennies in a stack of 4 pennies. –5. Make observations on a separate s heet of paper. –6. Flick a stack of 4 pennies in a stack of 4 pennies. –7. Make observations on a separate sheet of paper.

Wacky Penny Analysis 1. Explain your observations in terms of Newton’s 1 st Law. 2. Does the mass of an object effect the inertia? Explain?

Wacky Pennies Mass is the measure of inertia and if you change the mass the inertia will change

Balancing Act Purpose: To remove a card from underneath a penny and keep the penny balanced.

Balancing Act 1. Balance a card (index/playing) on your index finger. 2. Place a penny on top of the card over your finger and balance the two together. 3. Squarely hit/flick the side of the card with your other index finger. If you properly hit the card, where does the coin end up?

Please fill in the following chart with your observations, either at rest or moving: ObjectState of Motion At Rest/Moving Before it was hit During it being hit After it was hit Card Coin

Balancing Act Analysis 1. When does the object move? 2. How does this activity relate to the “pull the tablecloth” trick used by magicians?

2 nd law of motion The acceleration of an object depends on the mass of the object and the amount of force applied

Newton’s Second law of Motion Acceleration decreases if mass increases Acceleration increases if mass decreases Acceleration increases if force increases Acceleration decreases if force decreases

FORMULA F = M X A

Practice What is the force being applied to the car?

Other formulas to use A = F/M M = F/A

2 nd law of motion p?video_id=21643&title=Newtons_Law_2_ on_FMAhttp:// p?video_id=21643&title=Newtons_Law_2_ on_FMA Video Link Above

Newton’s 3 rd Law Action-Reaction: for every action there is an opposite and equal reaction.

Momentum The product of the mass and velocity of an object Formula: p= m x v p= momentum m= mass v= velocity  Units: kg x m/s (in a direction)

Conservation of Momentum Any time any objects collide, the total amount of momentum stays the same. –Example: Cue ball and billiard ball: Once you hit the cue ball it has a certain amount of momentum. It then hits the billiard ball All of the momentum is transferred to the billiard ball. Therefore, the total amount of momentum stays the same (opposite and equal reaction)

Finding Momentum An 85kg man is jogging with a velocity of 2.6 m/s to the North. Nearby, a 65kg man is skateboarding and is traveling with a velocity of 3 m/s North. Which person has a greater momentum? SHOW YOUR WORK! What is the momentum of an ostrich with a mass of 120kg that runs with a velocity of 16m/s north? SHOW YOUR WORK!