motion. force. newton's laws of motion.

Question 1

True or False?

You don’t have to see something move to know that it has moved.

Answer 1

TRUE

Question 2

How can you tell that something has moved even though you didn’t see it move?

Answer 2

Reference point(s)

Question 3

Motion definition

Answer 3

When an object changes its position relative to a reference point.

Question 4

How do you calculate speed?

Answer 4

speed = distance/time

Question 5

The motion of an object depends on the _________ _____ that is chosen.

Answer 5

reference point

Question 6

Distance def

Answer 6

How far it has moved according to its reference point.

Question 7

SI unit for distance

Answer 7

meter

Question 8

A runner jogs 50 meters. Then they turn around and run back to the 20 meter mark.

total distance ran = ?
displacement = ?

Answer 8

total distance ran = 80 meters

displacement = 20 meters

Question 9

What is force?

Answer 9

A push or pull

Question 10

Are the effects of force always noticeable?

Answer 10

No. Sometimes it is obvious that force has been applied, but other forces are not always noticeable.

Question 11

What can cause the motion of an object to change?

Answer 11

a force

Question 12

An example of Changing Motion

Answer 12

Playing Pool

• you can force a ball at rest to roll into a pocket by striking it with another ball
• the force of the moving the ball causes the ball at ret to move in the direction of the force

Question 13

How is net force created?

Answer 13

When two or more forces act on an object at the same time, the forces combine to form the NET FORCE.

Question 14

What is net force?

Answer 14

the sum of all of the forces acting on an object

Question 15

True or False?

The combining forces can only be balanced forces.

Answer 15

FALSE

The combining forces can either by unbalanced or balanced forces. —–> + –> = ——->

Question 16

Why do forces follow the same addition rules as displacement?

Answer 16

Because they have direction

Question 17

Do you add or subtract forces going in the SAME direction?

Answer 17

Add

Question 18

Do you add or subtract forces going in the OPPOSITE directions?

Answer 18

SUBTRACT

Question 19

True of False?

Forces going in opposite directions CAN be added together?

Answer 19

FALSE

forces NOT in the SAME direction (so opposite) CANNOT be added together.

Question 20

What is the SI unit for force?

Answer 20

newtons (N)

Question 21

What is an example of force being used to move something that might be 3 N to move at a constant speed.

Answer 21

It takes 3 Newtons of force to lift a can of soda at a constant speed.

Question 22

Think of Mrs. McMahon arm wrestling Isaiah, and say Isaiah won. One clearly is stronger than the other. Describe the net force between the two forces (unbalanced).

Answer 22

The net force that pushes the arm down is the difference between the two forces because they are in opposite directions. Because the net force is NOT zero, movement occurred. Mrs.M = net force —>

Question 23

True or False?

Unbalanced forces can never be in the same direction.

Answer 23

FALSE

Unbalanced forces CAN be in the SAME direction.

Question 24

What would be an example of unbalanced forces at work?

Answer 24

Example:
Imagine two people working together to push a vehicle that has run out of gas to a gas station.

The weight of the car that is opposing them is not enough to balance their combined effort, thus this is UNBALANCED.

They are pushing in the same direction, SO the forces can be ADDED to get the NET FORCE.

AGAIN movement OCCURS *SOOOO the net force is NOT ZERO.

Question 25

Think Mrs. McMahon vs Mrs. McMahon in an arm wrestling match. What would be happening with these forces?

Answer 25

These forces would cancel each other out.

Question 26

True or False? | Forces on an object that are EQUAL in size and OPPOSITE in direction are called UNBALANCED forces?

Answer 26

FALSE Forces on an object are equal in size and opposite in direction are called BALANCED forces.

Question 27

What is the net force if no movement occurs?

Answer 27

zero

Question 28

What is an example of friction?

Answer 28

Ex: The star soccer player kicks a ball and isn’t touched by any other players or objects.

Question 29

Take the example of friction: (The star soccer player kicks a ball and isn’t touched by any other players or objects) - will it keep moving with a constant speed forever?

Answer 29

No. The force that slows the ball and brings it to a stop if friction.

Question 30

Friction def

Answer 30

the force that opposes the sliding motion of two surfaces that are touching each other

Question 31

What does the amount of friction between two surfaces depend on? (two things)

Answer 31

1. the KIND/TYPE of surface(s) | 2. the force pressing the surfaces together

Question 32

How/ Why does friction occur? | 5 things

Answer 32

• microwelds - ALL surfaces have bumps and dips If two surfaces are in contact, wielding or sticking occurs where the bumps touch each other At these sticking points, MICRO-WELDS are formed The LARGER the force pushing the two surfaces together is, the stronger these micro-weld will be BECAUSE more of the surface bumps will come into contact For one surface to move over another, a FORCE must be applied to BREAK the microwelds

Question 33

STATIC Friction def

Answer 33

the friction that PREVENTS movement BEFORE it starts

Question 34

Think of an example of STATIC friction

Answer 34

Ex: Suppose you have filled a cardboard box with books and you want to move it. It’s too heavy to lift, so you start pushing on I️, but it’s doesn’t budge.

Question 35

What is happening in the example of static friction?

Answer 35

- the box is experiencing no change in motion SO the net force on the box is zero - the applied force was CANCELED out by friction - this is STATIC FRICTION

Question 36

Why does static friction prevent two surfaces from sliding past each other?

Answer 36

This is due to the microwelds that have formed between the bottom of the box and the floor If your push is not large enough to break, the microwelds, the box will not move

Question 37

SLIDING Friction def

Answer 37

the friction that opposes movement while it’s happening

Question 38

What is an example of SLIDING friction?

Answer 38

Ex: Suppose you get a friend to help you move the previously mention box (in static friction). Together, you have exerted enough force to BREAK the micro-welds and the box moves!

Question 39

What is the net force if something moves (vague) *like in SLIDING friction example

Answer 39

NOT zero

Question 40

Why must you continually move the box in the SLIDING friction example?

Answer 40

because the SLIDING Friction opposes the motion of the box as the box slides across the floor

Question 41

True or False? | SLIDING friction opposes the motion of 2 surfaces sliding past each other BEFORE it happens.

Answer 41

FALSE | It opposes WHILE it is happening

Question 42

Why does the sliding friction oppose the motion of 2 surfaces sliding past each other?

Answer 42

Because the micro-welds are constantly BREAKING and FORMING as the objects slide past each other.

Question 43

ROLLING Friction def

Answer 43

the friction that PREVENTS slipping DURING movement

Question 44

Give and example if ROLLING friction

Answer 44

Ex: As wheel roll over a surface static friction acts over the area where the wheel and surface touch PREVENTING the wheel from SLIPPING *called ROLLING friction

Question 45

What is ROLLING friction called when referring to tires on vehicles?

Answer 45

traction

Question 46

Name the four basic forces

Answer 46

1. Gravity 2. Electromagnet force 3. STRONG nuclear force 4. WEAK nuclear force