NEWTON’S SECOND LAW8TH GRADE

PGS. 556-559

FINISH AND COMPLETE

•FINISH FRICTION LAB

•REPEAT LAB IF NECESSARY

OBJECTIVES

STUDENTS WILL…

• EXPLAIN NEWTON’S SECOND LAW OF MOTION

• PRACTICE SOLVING EQUATIONS USING NEWTON’S SECOND LAW

•UNDERSTAND HOW GRAVITY IS RELATED TO WEIGHT AND MASS

FORCE AND ACCELERATION

NEWTON’S SECOND LAW OF MOTION

•STATES WHEN A FORCE ACTS ON AN OBJECT, THE OBJECT ACCELERATES IN THE DIRECTION OF THE FORCE.

•ACCELERATION (M/S 2)= NET FORCE (NEWTONS)

MASS (KILOGRAMS)

THINK ABOUT IT….

•THE FORCE NEEDED TO CHANGE THE MOTION OF AN OBJECT DEPENDS ON ITS MASS.

• IF YOU HAD 2 SHOPPING CHARTS-ONE THAT WAS EMPTY AND ONE THAT WAS FULL OF GROCERIES WHICH ONE WOULD BE EASIER TO STOP AND WHY?

•NEWTON’S SECOND LAW

GRAVITY

• WHAT DO YOU KNOW ABOUT GRAVITY? WHAT IS GRAVITY?

IT IS A FORCE THAT EXISTS BETWEEN ANY TWO OBJECTS THAT HAVE MASS. IT IS ATTRACTIVE AND PULLS OBJECTS TOWARDS EACH OTHER. (PG. 557)

If… Then Gravity…

Mass is larger

Mass is smaller

Distance increases

Distance decreases

GRAVITY

• WHAT IS THE DIFFERENCE BETWEEN MASS AND WEIGHT? (PG.558)

• ON MARS, THE WEIGHT WOULD ________ BECAUSE _______________.

• THE MASS WOULD _____________ BECAUSE _____________________.

Weight Mass

FOR NEXT TIME…

•READ PGS. 560-562. DEFINE CENTER OF MASS ON INDEX CARDS.

•FINISH FRICTION LAB IF NEEDED.

•EQUATION PRACTICE WITH NEWTON’S SECOND LAW ON BLUE.MSSCIENCE.COM

•HEAD PHONES/EAR BUDS FOR CLASS ON MONDAY.

VIRTUAL LAB: WHAT IS NEWTON’S SECOND LAW

OF MOTION?8TH GRADE

GAME PLAN

• FIND AND SIT WITH YOUR LAB PARTNER FOR TODAY.

• READ AND REVIEW THE DIRECTIONS FOR TODAY’S VIRTUAL LAB.

PARTNERS

• KELSEY/JESSICA JAKE/ALEC DJ/JACK CHESCA/LILLY

• RYAN/CONNOR JOSH/BRANDON MCKENNA/SARAH

• BRADLEY/AMBROS KAYLA/COURTNEY CHARLIE/JEREMY

• ANDREW/CALEB ELLA/ALEXIS

OBJECTIVES

STUDENTS WILL

• RELATE NEWTON’S SECOND LAW OF MOTION TO THE EFFECT OF GRAVITY ON FALLING OBJECTS

• DETERMINE THE EFFECT OF MASS ON THE ACCELERATION RATE OF FALLING OBJECTS

• OBSERVE THE EFFECT OF GRAVITATIONAL CONDITIONS ON THE RATE AT WHICH OBJECT OF IDENTICAL MASS FALL.

• GIVEN MASS AND ACCELERATION, COMPUTE FORCE.

VIRTUAL LAB

PLEASE TAKE WITH YOU TO THE COMPUTER LAB….

• LAB DIRECTIONS/WORKSHEET

• PEN/PENCIL

• CALCULATOR

• SCIENCE TEXTBOOK

FOR NEXT TIME…

•COMPLETE VIRTUAL LAB IF NEEDED.

NEWTON’S SECOND LAW8TH GRADE

CIRCULAR MOTION, AIR RESISTANCE, CENTER OF MASS

DO NOW….

•FOR THE FOLLOWING ACTIONS, EXPLAIN WHETHER THE FORCES INVOLVED ARE BALANCED OR UNBALANCED.

•A. YOU PUSH A BOX UNTIL IT MOVES.

•B. YOU PUSH A BOX BUT IT DOESN’T MOVE.

•C. YOU STOP PUSHING A BOX AND IT SLOWS DOWN.

WATCH IT!

•MASS AND WEIGHT

•A WORLD WITHOUT FRICTION

OBJECTIVES

STUDENTS WILL…

• EXPLAIN WHY THE DIRECTION OF FORCE IS IMPORTANT IN CIRCULAR MOTION AND AIR RESISTANCE

• DESCRIBE THE CENTER OF MASS IN REGARDS TO MOTION

• KHAN ACADEMY

USING NEWTON’S SECOND LAW (PG. 558-560)

Acceleration Direction of Force

Speeding Up

Slowing Down

Turning

USING NEWTON’S SECOND LAW

• NEWTON’S SECOND LAW OF MOTION CAN BE USED TO CALCULATE ACCELERATION.

• TRY THESE PRACTICE PROBLEMS. (REMEMBER THE EQUATIONS!)

• 1) A NET FORCE OF 4,300 N ACTS ON A CAR WITH A MASS OF 1,600 KG. WHAT IS THE ACCELERATION OF THE CAR?

• 2) A BOOK WITH A MASS OF 2 KG IS PUSHED ALONG A TABLE. IF THE NET FORCE ON THE BOOK IS 1 N, WHAT IS THE BOOK’S ACCELERATION?

• 3) A BASEBALL HAS A MASS OF 0.15 KG. WHAT IS THE NET FORCE ON THE BALL IF ITS ACCELERATION IS 40 M/S 2?

Definition:

Examples of Circular Motion:

Centripetal Force:

Circular MotionVideo

Circular MotionPg: 560-561

FOR NEXT TIME…

• READ PGS. 563-568

•DEFINE NEWTON’S THIRD LAW ON INDEX CARD

•WATCH NEWTON’S SECOND LAW ON KHAN ACADEMY WEBSITE

• THIS IS ALL DUE FRIDAY, 11/1!

DROP THE OBJECT ACTIVITY:

EXPLORING AIR RESISTANCE

8TH GRADE

REVIEW TIME

•WITH YOUR LAB GROUP, ANSWER THE QUESTION ON THE INDEX CARD. BE PREPARED TO SHARE YOUR ANSWER WITH THE REST OF THE CLASS.

Definition: a form of friction that acts to slow down any object moving in the air.

Gets larger when: object moves faster

Depends on: size and shape of an object

Terminal Velocity (aka final velocity): an object falling at a constant speed when air resistance balances the

force of gravity

Air ResistancePg. 561

CENTER OF MASS

•CENTER OF MASS-IS THE POINT IN AN OBJECT THAT MOVES AS IF THE OBJECT’S MASS WERE CONCENTRATED AT ONE POINT.

•FOR SYMMETRICAL OBJECTS (LIKE A BALL): THE CENTER OF MASS IS AT THE OBJECT’S CENTER.

•FOR OTHER OBJECTS: THE CENTER OF MASS IS WHERE THE NET FORCE IS BEING APPLIED.

ACTIVITY- HOW DOES AIR RESISTANCE AFFECT FALLING OBJECTS?

•REVIEW DIRECTIONS AND PROCEDURES

•COMPLETE ACTIVITY WORKSHEET

•QUESTIONS?

SELF CHECK QUESTIONS

•WITH YOUR LAB GROUP, COMPLETE SELF-QUESTIONS #2-6 PG. 568 IN YOUR SCIENCE NOTEBOOK.

•CHECK AND REVIEW QUESTIONS.

FOR NEXT TIME….

•ON KHAN ACADEMY, TAKE THE QUIZ ON ALL OF NEWTON’S LAWS OF MOTION.

•ALL KHAN ACADEMY HOMEWORK ON NEWTON’S LAW’S DUE FRIDAY!

•FINISH SELF-CHECK QUESTIONS #2-6 PG. 658 IF NEEDED