Newton’s Third Law

DO NOW: 5 MINUTES DO NOT COPY PROBLEMS Look back to the definition of Newton’s Third Law and use it to answer the following question. The mass of a mouse is less than an elephant, so if I apply the same force to both animals which will accelerate more? Justify your answer.

Announcements This week: Finish Newton’s Laws & Quiz at end of week! Quiz 1 Make-up after school Tuesday (ONLY DAY!!!) Tennis interest meeting Wednesday after school Exit tickets – 100 on quiz, every question wrong is (-1) Student of the month Each class, student who shows ALL of our class values that month Picture on wall, prize, & HW pass!

Newton’s Third Law: Newton’s 3rd Law says that for every action force, there is an equal and opposite reaction force.

Alternate Definitions: Newton’s Third Law  Choose one to add to your notes “To every action there is always an equal and opposite reaction.” “The forces of two bodies on each other are always equal and are directed in opposite directions.” “A force acts between a pair of objects, and not on a single object. So each and every force has two ends. Each of the two ends is the same except for being opposite in direction. The ends of a force are mirror images of each other.”

Examples: Standing on the ground Person exerts a force pushing down Ground exerts a force pushing up on the person A fish pushes backwards on the water, and this propels his body forward. Fish pushes on water Water pushes back on fish

Balancing Forces (Paired Forces) Person and Toy Car Ground pushing back on man Toy car pulling on man Man pulling on toy car Man pushing off of ground

Demo: Demo: Man pulling car on String Man applying a force on the toy car What does Newton’s 3rd Law say is happening???? Car is applying an EQUAL and OPPOSITE force on man! So why is the car moving?! Answer: The man’s mass is greater than the cars!

Take-Away Point: (2 mins) (Write down 1 take away point (something you need to remember) about Newton’s 3rd Law. COMPLETE SENTENCES. IN YOUR NOTES The amount of force applied to an object of a certain mass determines its acceleration.

Negative Sign indicates the opposite direction! F -F

Practice: Negative Sign Two people pushing each others hands

Class Practice 1 OF 2 (REFRESHER) 1. A car with a mass of 2000 kg is accelerating at a rate of 2 m/s2. What is the car’s force?

Class Practice 2 OF 2 2. Two wrestlers, Davon and Chris, are wrestling in a match. Davon has a mass of 70kg and Chris has a mass of 65 kg. Davon is exerting a force of 14 N on Chris. How much force is Chris exerting on Davon? Calculate Chris’s and Davon’s acceleration. Who is being pushed backwards?

Worksheet Practice Worksheet is a class set, DO NOT WRITE ON! Do not copy the problems Write complete answers in your notebook Do your best on every problem Raise you hand if you have questions and wait patiently for me Look through your notes again while waiting

Write Quiz: (10 mins) 1 piece of paper with all group members names on it 5 question quiz to STUMP your classmates Write the correct answers on a SEPARATE piece of paper For every question your classmates answer correctly, THEY get a point For every question you stump your classmates on YOU get a point Get quizzes signed by me during the 10 minutes

Take Quiz: (10 mins) Pass quizzes clockwise Show work and answer questions directly on the quiz paper Submit work to me within the 10 minutes

Newton’s Three Laws Brochure 3 fold piece of paper Each fold will correlate to one of Newton’s Laws For each law: Definition IN YOUR OWN WORDS Example  illustration Practice Problem and answer (IF ITS GOOD YOU WILL SEE IT AGAIN ON THE QUIZ)

Some Examples

Another Example

Rubric

Last Note Not good at drawing? Are you an artist? That’s okay, the picture doesn’t have to be amazing Just be sure the picture clearly shows Newton’s Law Make sure the picture looks like you put time into it (even if it is not perfect!) Are you an artist? Be sure you are not getting hung up on drawing! You still need to complete this assignment in class today Do NOT spend all of your time on the picture portion

Exit Ticket What are Newton’s Three Laws of Motion? Give an example of Newton’s third law of motion using complete sentences. Reminder, Quiz on Newton’s 3 Laws is Thurs/Friday(or next time you are in this class)