1.1. What is a What is a ForceForce??

Page #:_____ Paragraph Page #:_____ Paragraph #: ___#: ___

AnswerAnswer::• Force is push or pullForce is push or pull

Write an Example :Write an Example :• Throwing a baseballThrowing a baseball

3636 22

2. 2. The combination of The combination of all all the forcesthe forces acting on an acting on an

object is called?object is called?

Page #:_____ Page #:_____ Paragraph #:___Paragraph #:___

AnswerAnswer::• The The Net ForceNet Force

3737 11

3. When 3. When 2 forces2 forces cancel cancel each other out and they each other out and they don’t change the object’s don’t change the object’s velocity, they are called?velocity, they are called?

Page #:____ Paragraph Page #:____ Paragraph #:____#:____

AnswerAnswer::

BalancedBalanced Forces Forces

3377

33

4. 4. When the forces are When the forces are BalancedBalanced,,

the the net forcenet force is is??

Page #:______ Paragraph Page #:______ Paragraph #:____#:____

AnswerAnswer::

The net force is The net force is zerozero

Object’s speed/velocity Object’s speed/velocity didn’t changedidn’t change

3377

33

5. If the forces on an 5. If the forces on an object are object are UnbalancedUnbalanced, ,

the objects velocity the objects velocity changeschanges....

Page #:_____ Page #:_____ Paragraph #:___Paragraph #:___

T or FT or F

AnswerAnswer::

TrueTrue

3377

33

6. Which 6. Which ItalianItalian scientist scientist before Isaac Newton before Isaac Newton

understood how forces understood how forces work?work?

Page #:____ Page #:____ Paragraph #:___Paragraph #:___

AnswerAnswer::• Galileo GalileiGalileo Galilei

3838 33

77. Describe in-full . Describe in-full Newton’s First Law of Newton’s First Law of

Motion:Motion: Page #:______ Paragraph #:____Page #:______ Paragraph #:____

AnswerAnswer::• If the If the net forcenet force on an object is on an object is

zerozero,, the object will the object will remainremain at at restrest,, or if it’s moving, it will or if it’s moving, it will continue movingcontinue moving in straight in straight line at line at constantconstant speed. speed.

3838 44

8. What is 8. What is FrictionFriction?? Page #:_____ Paragraph Page #:_____ Paragraph #:_____#:_____

AnswerAnswer::• The force that brings The force that brings

nearly everything to a nearly everything to a

STOP!!STOP!! Resists sliding between Resists sliding between

2 objects2 objects

3388

11

9. 9. Give example of how Give example of how FrictionFriction works works..

Page #:_____ Paragraph #:_____Page #:_____ Paragraph #:_____

Answer:Answer:• Friction Friction will eventually bring will eventually bring

youryour

skateboard to a stop, unless you

keep pushing on it… keep pushing on it…

3388

11

10.10.What do the different What do the different types of Frictiontypes of Friction have in have in

common? common? ((Reading CheckReading Check))

Page #:____ Paragraph #:___Page #:____ Paragraph #:___

AnswerAnswer::• The The Frictional ForcesFrictional Forces always always

try try

to prevent one object from to prevent one object from slidingsliding

on the other object.on the other object.

3399

11

11. What causes 11. What causes Static Static FrictionFriction??

Page #:_____ Paragraph #:___Page #:_____ Paragraph #:___ AnswerAnswer::

• It is caused by the It is caused by the attraction attraction between the atoms between the atoms on the two on the two surfaces that are in contact.surfaces that are in contact.

• The The smoothersmoother the surfaces the the surfaces the less attraction between the less attraction between the atomsatoms!!!!

4400

22

11. What causes 11. What causes Static Static FrictionFrictioncont…….cont…….

• Static Friction prevents an object at rest from moving when a force is applied

12.12.Static FrictionStatic Friction acts on acts on an an

object at rest.object at rest. Page #:_____ Page #:_____ Paragraph #:_____Paragraph #:_____

True or FalseTrue or False

AnswerAnswer::• TrueTrue

4400

33

13. What does 13. What does Sliding Sliding FrictionFriction do? do?

Page #:____ Paragraph Page #:____ Paragraph #:____#:____

AnswerAnswer::• Sliding friction Sliding friction slows slows

down an object that down an object that

slidesslides

4400

11

14. What causes 14. What causes Rolling Rolling FrictionFriction??

Page #:_____ Paragraph #:_____Page #:_____ Paragraph #:_____

AnswerAnswer::• Rolling friction Rolling friction occurs when occurs when

an object rolls across a surface.an object rolls across a surface.• Example:Example:

Bicycle wheel rolling Bicycle wheel rolling

on the groundon the ground

a grounda ground

4141 11

15. Which 15. Which Frictional Frictional ForceForce is is strongerstronger??

Page #:______ Paragraph Page #:______ Paragraph #:____#:____

A.A. Rolling FrictionRolling Friction between wheels between wheels

and groundand ground

B. B. Sliding FrictionSliding Friction between box between box

and groundand ground• AnswerAnswer: :

B – B – Sliding FrictionSliding Friction

4141 22

Review questionsReview questions1. How would you describe a Force?

Answer: Push or a Pull

2. What is Net Force?

Answer: Combination of all the Forces

3. Describe what it means when forces are Balanced?

Answer: The forces acting on the object

are equal. Object does not move.

Review questionsReview questions4.4. What is the What is the Net forceNet force when when ForcesForces

areare

BalancedBalanced??

AnswerAnswer: Net force is “: Net force is “Zero”Zero”

Object stays where it Object stays where it is!!!!!!is!!!!!!

Both boys are using sameBoth boys are using same

Force or pushing equally.Force or pushing equally.

The The DOOR DOESN’TDOOR DOESN’T

MOVEMOVE!!!!!!!!!!!!!!

Review questionsReview questions5.5. What happens when What happens when ForcesForces are are

UnbalancedUnbalanced??

AnswerAnswer: : UnbalancedUnbalanced Forces are Forces are not not

equal and the object equal and the object will move!!!will move!!!

The boy on the left is usingThe boy on the left is using

greater forcegreater force, therefore he is, therefore he is

pushing the door towardpushing the door toward

the boy on the right!!!the boy on the right!!!

Review questionsReview questions

6.6. What are the 3 types of What are the 3 types of FrictionFriction

or or Frictional forcesFrictional forces??

Answer:Answer:

StaticStatic friction friction

SlidingSliding friction friction

RollingRolling friction friction

Review questionsReview questions7. How is Force measured?Answer: In a unit called Newton8. What is a Newton?Answer:

One Newton (symbol NN) is the forcethat will give an object whose is

mass 1kilogram an acceleration of 1 meter

persecond squared.

N=1 kg·m/s²N=1 kg·m/s²

Review questionsReview questions9. In a tug of war, one student is

pulling on a rope with a force of 10N and the other student with 8 N. What is the Net force on the rope? Or, the actual amount of force pulling on the rope?

Answer:It is the difference between

the stronger and the weaker force

10N – 8N = 2N10N – 8N = 2N

Review questionsReview questionsStudy the diagram carefully and answer the questions

10. Are the 10. Are the ForcesForces on on the box the box BalancedBalanced or or UnbalancedUnbalanced?? Answer:

Unbalanced 11. What is the Net Force on the box?

Answer: 45N – 30 N = 15N

Net force is 15NNet force is 15N

45N

30NWe

stEast

Review questionsReview questions

12. In which direction did the box move? Answer:

The box moved East

45N 30N

West East