Balloon Rocket Lab A Preview of the lab Friday After the Quiz

Science 7 Darren Nigh Sir Isaac Newton’s Three Laws of Motion

Isaac Newton Born 1642 Went to University of Cambridge in England as a student and taught there as a professor after Never married Gave his attention mostly to physics and mathematics, but he also gave his attention to religion and alchemy Newton was the first to solve three mysteries that intrigued the scientists –Laws of Motion –Laws of Planetary Orbits –Calculus

Famous Quotes If I have seen further it is by standing on the shoulders of giants I can calculate the motion of heavily bodies but not the madness of people A man may imagine things that are false, but he can only understand things that are true To every action there is always opposed an equal reaction

Major Achievements The invention, design and construction of a reflecting telescope (1668) –He ground the mirror, built the tube, and even made his own tools for the job -- The mirror gave a sharper image than was possible with a large lens because a lens focuses different colors at slightly different distances, an effect called chromatic aberration. –This was a real advance in telescope technology, and ensured his election to membership in the Royal Society Newton realized that the moon’s circular path around the earth could be caused by the same gravitational force that would hold a fired cannonball in low orbit, in other words, the same force that causes bodies to fall. His three Laws

Laws The First Law –Law of inertia –An object at rest stays at rest objects in motion stays in motion The Second law –Law of acceleration –Force equals mass times acceleration The Third law –Law of Interaction –For every action there is an equal and opposite reaction

Three Laws of Motion Newton’s First Law The Law of Inertia Newton’s Second Law The Law of Acceleration Newton’s Third Law The Law of Interaction

I. The 1 st Law of Motion

Law of Inertia An object at rest will remain at rest, and an object in motion will remain in motion with constant velocity unless acted upon by an external force. In other words….

For example:

A boy stopping ball #1 or kicking ball #2 would be an outside force. Outside Force:

When driving a car, the seat belt provides the unbalanced force which brings you from a state of motion to a state of rest. Perhaps you could speculate what would occur when no seat belt is used.

If the truck were to abruptly stop and the straps were no longer functioning, then the ladder in motion would continue in motion

II. The 2 nd Law of Motion

The acceleration of an object increases with increased force and decreases with increased mass Law of Acceleration

It accelerates in the direction that you push it. If you push twice as hard, it accelerates twice as much. If it receives twice the mass, it accelerates half as much.

For Example: A ball is in motion and it has a certain velocity (speed/acceleration) that it will maintain. The ball’s velocity will change if acted upon by an outside force.

If the surface the ball is rolling on were to slant, the ball’s velocity would change and the ball would move faster. The slant would be considered the outside force.

III. The 3rd Law of Motion

Law of Interaction In every action, there is always an equal and opposite reaction

As the man jumps off the boat, he exerts the force on the boat and the boat exerts the reaction force on the man. The man leaps forward onto the pier, while the boat moves away from the pier. Newton’s Third Law

The elephant's feet push backward on the ground; the ground pushes forward on its feet. The right end of the right rope pulls leftward on the elephant's body; its body pulls rightward on the right end of the right rope. The left end of the right rope pulls rightward on the man; the man pulls leftward on the left end of the right rope. The right end of the left rope pulls leftward on the man; the man pulls rightward on the right end of the left rope. The tractor pulls leftward on the right end of the left rope; the left end of the left rope pulls rightward on the tractor. etc., etc.

Click for more understanding. up, up and AWAY! Let's study how a rocket works to understand Newton's Third Law.

For Example: Imagine you are riding a skateboard…

Now imagine that you are not very good at riding the skateboard and you fall forward…

According to Newton’s Third Law, as you fall in one direction, there is an opposite reaction occurring in the other direction. Basically, as you fall forward, the skateboard will move in the other direction.

Instant Review---Laws The First Law –Law of inertia –An object at rest stays at rest objects in motion stays in motion The Second law –Law of acceleration –Force equals mass times acceleration The Third law –Law of Interaction –For every action there is an equal and opposite reaction

Centripetal Force Any force that keeps an object moving in a circle is known as Centripetal Force. The force points toward the center of the circle Without Centripetal Force, the object would go flying off in a straight line

Momentum The momentum of an object is the product of its mass and velocity. At the same velocity a wrecking ball has more momentum then a tennis ball However, if you compare two wrecking balls of the same size, the faster wrecking ball has the most momentum.

Collision A situation in which two objects in close contact exchange energy and momentum As another car bumps into the back of yours, the force pushes your car forward. Some of the momentum of the car behind you is transferred to your car At the same time the car behind you slows because of the reaction force from your car You gain momentum and the other car loses momentum

Conclusion Forces change motion Objects at rest remain at rest, objects in motion remain in motion at the same velocity unless acted upon by an unbalanced force Force and Mass determine acceleration The acceleration of an object increases with increased force and decreases with increased mass

Forces act in pairs When an object exerts force on another object, the second object exerts an equal and opposite force on the first object Forces transfer momentum Momentum is a property of a moving object Forces in collisions are equal and opposite Momentum is conserved in collisions