Name _________ Hour __ Group # __Test Date ___

Physics #2 - Forces Notebook

Force Website:

https://phet.colorado.edu/en/simulation/forces-and-motion-basics

Physics #2- Vocabulary 1. Force - A push or a pull.

2. Spring Scale - A tool used for measuring force.

3. Newton - Unit to represent force.

4. Friction - Opposing force caused by two objects rubbing against each other.

5. Gravity - A force that pulls objects together.

6. Inertia - The tendency of an object to keep doing whatever it is doing.

7. Net Forces - The combination of all forces acting on an object.

8. Balanced Forces - Two or more equal forces, which cancel each other out, preventing a

change in motion.

9. Unbalanced Forces - Two or more unequal forces acting on an object, causing the

object to accelerate.

Physics #2 - LEARNING TARGETS

I can explain force.

I can explain inertia.

I can use an arrow diagram to identify all forces acting on an object.

I can explain how friction affects motion.

I can calculate the net force acting on an object.

I can describe how net force affects the motion of an object.

I can describe the motion of an object when all opposing forces are

balanced or unbalanced.

I can define and give examples of Newton’s 3 Laws of Motion.

A soccer ball sits on the ground, motionless, until

you kick it. You hold your book above the ground,

then let it go, gravity pulls it to the floor. An

object will speed up, slow down or turn only if

something is pushing or pulling it. A force is a ________ or a

_________. A force can cause an object to ____________ or

____________. Force is measured in units called ___________

abbreviated as ____. 1 N = 1 kg • m/s2

The tool used to measure force is called a

__________ ________.

The unit of force is named after Sir Isaac

Newton. He was an ___________ physicist and

mathematician who lived from 1642-1727.

Think about what happens when you try to stop someone who is rushing toward you.

A small child is easy to stop. A large adult is harder to stop. The more mass an

object has, the harder it is to change its __________.

This tendency of an object to resist a change in motion is called

____________. Inertia applies to both moving and stationary objects.

If an object is moving, inertia causes it to continue ____________. If an

object is at rest, inertia causes it to stay at _______.

Your teacher will show you a scenario on a website. (Click on Motion”)

Put Newton’s 1st Law of Motion in your own words:

Inertia is Newton’s 1st law of Motion!

Newton’s 1st Law states that: An object in motion

will remain in ____________ at a

constant speed unless acted upon by a force. An

object that is not moving will remain at

__________ until acted upon by a force.

Examples of this Law: A comet in space will continue ________ at a

constant speed. A rolling soccer ball will come to a stop (due to the force of

friction) and remain _________ until acted upon by another force.

Prior to Isaac Newton’s 1st Law of Motion, many people that objects had a natural

tendency to be at ____________.

Newton’s 1st Law is the reason we need

seatbelts! The seatbelt “connects” you

to the car. So, when the car stops, you

_________. Without a seatbelt,

when the car stops you

_________________. Ouch!

The applied force is the force causing the

motion of the object due to a

_________ or _______.

In other words, the applied force is the

force put on an object by a person or another object and the

object usually moves in the direction of the applied force.

Examples of applied force are: ________________________

_______________________________________

Friction is the force exerted by a surface

as an object moves across it. In other

words, friction is the force that

________ down an object’s motion

and brings nearly everything to a

________. Friction is the

________ force caused by two objects rubbing against each other. The

force of friction is always __________ to the direction of motion.

Air resistance is a type of friction. Brakes on your bike

wheel are an example of friction.

Other examples of friction are: _____________

____________________________

Your teacher will show you a scenario on a website. (Click on “friction”)

Describe what friction does based on what you saw.

GRAV I TY

NORMAL FORCE

The force of Gravity is the force with which the

Earth, Moon, or other massively large object attracts

another object towards itself.

On Earth, gravity always pulls ________

towards the ground.

The force of gravity causes all

objects (regardless of whether it is a feather or a hammer!)

on or near the surface of the Earth to fall with an

acceleration of _____ m/s2.

The normal force is the support force acting on the

object that is in contact with,. In other words it is

the force caused by an object pushing

_________ on another object which is

pushing on it.

For example, if a book is resting on a surface, then

the surface is exerting an _______ force upon

the book in

order to support the weight of the book.

The normal force is

____________ to the surface.

An example is the ground pushing __ on

your feet.

Practice labeling each force (friction/applied/gravity/normal) in the following force diagrams.

Mass

Match each force with its correct description and exampled.

Description Force Example

A. Pulls toward Ground ___Applied____ 1. I lean against the wall and the

wall pushes on my back

B. Causes motion due

to push or pull ___Friction____ 2. You push a toy car

C. Caused by rubbing ____Gravity___ 3. Raindrops fall on your head

D. Support Force ___Normal____ 4. A soccer ball rolls to a rest

Label each force in the diagrams below. Use the terms: Friction, Gravity, Applied and Normal.

More than one force can act on an object. If you hold a paper

clip near a magnet, you, the magnet, and gravity all exert

forces on the paper clip. The combination of all the forces

acting on an object is called the _________ force.

Balanced Forces- Forces are _______________ when the

two opposing forces have the ________ strength and are working

_______________ each other. These forces will _________

each other out. When the forces are balanced there is no change in the object’s

_________. If it was at rest, it will ______ at rest. If it is moving it

will keep moving at that ________ constant speed. The NET force acting on

the object will be ____ Newtons.

Pulling with balanced forces in different directions… If this object is at rest it will _____________________________________________________________ If this object is moving it will _____________________________________________________________

Your teacher will show you a scenario on a website.

Predict what BALANCED and UNBALANCED forces are:

Unbalanced Forces- Forces are ____________ when one

force is _____________ than the other force, and the forces do not

_________ each other out. To overcome inertia there must be an

____________ forces acting on the object. Unbalanced forces cause the

the object to ____________ or ______________.

\

Forces that don’t cancel each other out are called _______________ forces.

Forces that cancel each other out are called ___________________ forces.

Pulling with unbalanced forces in different directions…

If this object was at rest it will ____________________________________________________________ If this object was moving it will _____________________________________________________________

Pulling and pushing with unbalanced forces in the same directions…

If this object was at rest it will ____________________________________________________________ If this object was moving it will _____________________________________________________________

Unbalanced forces = acceleration

Applied Force From the engine

Friction Force From air resistance

Newton’s 2nd law describes unbalanced forces.

Unbalanced forces will cause an object to ________________ in the

direction of the Net force. The greater the force the ___________the

acceleration. Newton’s 2nd Law can

also be written as a formula. …

Force = mass X acceleration F = m x a

Another way of saying this is:

acceleration = Force / mass

a = F/m

Try This:

The force acting on a 3 kg toy car accelerating at 2 m/s2 would be…

Force = mass X acceleration

Force = ___ kg X ____ m/s2 = _____________

What will the force be to have a 6 kg toy car accelerate 2 m/s2?

Force = mass X acceleration

Force = ___ kg X ____ m/s2 = _____________

This means that the greater the mass, the _______ force is needed to cause

the same acceleration.

If these two kids are pulling with the same

amount of force the ___________

rock will accelerate more.

Forces working together: When forces are in the same direction you will

_____ them together. ( + ) The resulting total force is the ______

force. Net means _______ the forces working on the object. The object will

move in the __________ of the net force.

Forces working against each other: When forces are in opposite

directions you will ___________ them from each other. ( - ) The

difference between the opposing forces is the _______ force. The movement

will be in the direction of the ______________ force.

If one force is greater than the other then the object will ______________ in

the direction of the _______________ force.

Pushing with forces in the same direction… Balanced or Unbalanced forces? _______________________ What is the Net force on the box? ___________ What direction? _________________ If this object was at rest it will _____________________________________________________________ If this object was moving it will _____________________________________________________________

Pulling with forces in different directions…

Balanced or Unbalanced forces? _______________________

What is the Net force on the box? ___________ What direction? _________________ If this object was at rest it will _____________________________________________________________ If this object was moving it will ______________________________________________________________

12N 5N

15N 5N

If both forces working against each other are equal, and the net force is _______ then the object will not _______________. If it is at rest it will remain at ___________ or if it is moving it will continue ____________ at a constant _____________.

Are all opposing forces acting

on the boat balanced? ______

What is the net force on the

boat? __________________

What is the direction of the

net force? ______________

Will the boat accelerate?

_____________

Pulling with forces in different directions…

Balanced or Unbalanced forces? _______________________ What is the Net force on the box? ___________ What direction? _________________ If this object was at rest it will _____________________________________________________________ If this object was moving it will ______________________________________________________________

7 N

Are all opposing forces acting on

Thomas the Train balanced? ____

What is the net force on Thomas

the Train? __________________

What is the direction of the net

force? ____________________

Will Thomas the Train accelerate?

__________________________

7 N

Collisions

If you’ve ever played billiards (“pool”), you

know that when the cue ball hits another ball,

the motion of both balls change. The cue ball

_____________________ and may change

direction. Meanwhile, the other ball starts

_________________.

This is true for any collision, as long as no

outside _________________ such as friction

act on the objects and change their speeds after the collision.

Not only does this happen with billiard balls, but with atoms, cars, football

players, or any other matter.

Let’s see what happens when objects of different masses collide.

When a less massive marble strikes a more massive marble that is at rest, the

smaller will bounce off in the __________________ direction. The larger

marble moves slowly in the ___________ direction that the small one was

originally moving.

When a large marble strikes a small marble that is at rest, both will move in

the ______________ direction. The smaller marble will always move

_________________ than the larger one.

If two objects of the same mass move at the same speed and collide head-on,

the will rebound and move with the same speed in the ___________ direction.

–

Newton’s 3rd law of motion describes something that happens

when one object exerts a force on another object. Newton’s 3rd Law

states: when one object exerts a force on another object, the second

object exerts an __________ force in the

______________ direction.

“For every action, there is an equal but

opposite reaction.”

Examples-

When you stand, your body exerts the

________ force of its weight on the

surface of the Earth. At the same time, the Earth pushes against

your feet with an ________ but ___________

upward force. If this didn’t happen, you would _____ into the ground.

If you step off a boat onto the bank of a lake, you will move in the direction of the shore,

but the boat moves in the _____________ direction (leaving us face down in

the water, if we aren't careful!).

Two teenagers are standing on the ice facing each other. Assume that there is zero

friction produced by the ice surface. The weight of one of the teenagers is more than

the other. Now, they push each other in the opposite direction. Who will move away with

higher speed? __________________________.

Say you are watching a baseball game. Suddenly a foul ball comes in your direction. You

manage to push the ball away from you with your hands. However, the impact of the ball

causes pain in your hands. Why does this happen? This is because when two objects

interact with each other, each exerts ___________ and

_____________ forces on each other.

Examine the diagrams below and answer the questions.

18 N 12 N

Are all opposing forces balanced? ______ What is the net force?______________ Does this object accelerate? __________ If so, what direction?_______________

Are all opposing forces balanced? ______ What is the net force?______________ Does this object accelerate? __________ If so, what direction?_______________

23 N 23 N

75 N 50 N

12N

12N

85 N 55 N

40N

40N

70 N 70 N

60N

60N

100 N 180 N

120

N

120

N

You’re the Scientist #2 - Newton’s Laws

Cut the “Newton’s Law” paper as instructed by your teacher. Glue/paste it below. Under Isaac Newton give a short biography. Under each of the laws, define it and give an example

You’re the Scientist #3 - Examples of Newton’s Laws

Cut the “Newton’s Law” pockets and glue/paste it below as instructed by your teacher. Then cut out the 10 examples on the second page. Place them in the correct pocket. If time, come up with examples of your own and add them to the pockets!