108 Newton’s Second Law Notes Newton’s Second Law Notes10711/20/2014 Starter: 11/20/2014 Practice/Application: Glue here when done Newton’s Second Law Notes Newton’s Second Law Notes Connection: Calculations. Turn in when complete Copy Triangle here Exit: What is the force exerted when a 5kg bowling ball is dropped on a toe? Force or No Force? Two friends observe a piece of paper that falls from a 5 story building. The friends disagree about whether forces were acting on the piece of paper. This is what they say: Jorge: “I think things have to touch in order to have a force between them, so no forces were acting on that piece of paper.” Sarika: “I don’t think things have to be touching to have force between them, so I do think forces were acting on the piece of paper.” Which friend do you agree with? ____________ Explain your thinking. Provide examples that support your ideas about forces.

November 20, 2014 AGENDA 8.6 C Students will investigate and describe applications of Newton’s by reading and writing during an activity. 1 Starter 2. Notes 3. Activity 4. Exit

Force = mass x acceleration F am X ÷÷ Force = newtons (N) mass = grams (g) acceleration = (m/s/s )or (m/s 2 )

DateLecture/ Activity/ Lab Page Table of Contents 11/3 Speed, Velocity, and Acceleration Notes /4 Speed and Velocity Lab /5 Interpreting Graphs /6 Walking Lab II with graphing /10 Balanced and Unbalanced Forces /12 Newtons 1 st Law /13 Newton’s First Law Lab /14 Newton’s First Law Writing /17 CBA review /19 Newton’s First Law Lab # /20 Newton’s Second Law

Newton’s Second Law TEKS 8.6A demonstrate and calculate how unbalanced forces change the speed or direction of an object’s motion TEKS 8.6C investigate and describe applications of Newton’s law of force and acceleration

Net Force, Mass and Acceleration

Isaac Newton discovered one of the most important laws of nature; the relationship between net force, mass (inertia) and acceleration.

Newton’s second law states that the net force acting on a mass causes the mass to accelerate in the direction of the net force.

A shorthand way of writing this law is: f = ma f = force in newtons (N) m= mass in kilograms (kg) a = acceleration in meters per second per second (m/s 2 )

Objects with more mass are more difficult to accelerate.

If the same force is applied to two objects with different masses, the one with the smaller mass will accelerate more.

More mass means less acceleration, unless a larger force is applied.

small mass leads to large mass leads to large acceleration Same Forces small acceleration

small mass can lead to large mass same acceleration small force large force Different Forces

Falling Objects and Newton’s 2nd Law

Galileo Galilei, the Italian physicist and astronomer, studied falling objects.

He found that when two objects of different masses are dropped, they fell at the same rate.

This was never fully understood until Isaac Newton announced his second law of motion.

In the case of free falling objects, the force is equal to the weight of the object, which is determined by the acceleration of gravity (9.8 m/s 2 ).

Try dropping a book and a ball of paper. See what happens.

Now try dropping a piece of paper and a book. Most likely you will see that the paper falls more slowly.

Remember the book has more weight than the paper, so it has more force to resist friction from the air.

Try dropping the book with the paper against the lower surface of the book. What happens?

Now try dropping the book with the paper on top of the book. How will the accelerations of the book and the paper compare? Will they separate and fall differently?

How much force will be required to move the object in each picture? 2 m/s 2 m=50kg f = m=2000 kg.05 m/s 2 f= 100N 100N

What direction are the forces applied in each picture? 2 m/s 2 m=50kg f = m=2000 kg.05 m/s 2 f= left right

Will the rock and the van accelerate at the same rate? 2 m/s 2 m=50kg f = m=2000 kg.05 m/s 2 f= No, the rock will accelerate faster.

108 Newton’s Second Law Notes Newton’s Second Law Notes10711/20/2014 Starter: 11/20/2014 Practice/Application: Glue here when done Newton’s Second Law Notes Newton’s Second Law Notes Connection: Calculations. Turn in when complete Copy Triangle here Exit: What is the force exerted when a 5kg bowling ball is dropped on a toe? Force or No Force? Two friends observe a piece of paper that falls from a 5 story building. The friends disagree about whether forces were acting on the piece of paper. This is what they say: Jorge: “I think things have to touch in order to have a force between them, so no forces were acting on that piece of paper.” Sarika: “I don’t think things have to be touching to have force between them, so I do think forces were acting on the piece of paper.” Which friend do you agree with? ____________ Explain your thinking. Provide examples that support your ideas about forces.