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1. Investigate what is needed to describe motion completely.

2. Compare and contrast speed and velocity.

3. Learn about acceleration.

2. Compare and contrast speed and velocity.

3. Learn about acceleration.

1.
Force and Motion Standards

• S8P3 Students will investigate the

relationship between force, mass, and the

motion of objects.

• a. Determine the relationship between

velocity and acceleration.

• b. Demonstrate the effect of balanced and

unbalanced forces on an object in terms of

gravity, inertia, and friction.

• S8P3 Students will investigate the

relationship between force, mass, and the

motion of objects.

• a. Determine the relationship between

velocity and acceleration.

• b. Demonstrate the effect of balanced and

unbalanced forces on an object in terms of

gravity, inertia, and friction.

2.
What do we need to know and

be able to do?

I CAN explain how the quantity and direction of

velocity and acceleration related,

I CAN identify all forces acting on objects in

motion or at rest.

I CAN explain the advantages of using each of

the six simple machines to do work.

I CAN predict changes in gravitational force as

a result of changes in mass and/or distance.

be able to do?

I CAN explain how the quantity and direction of

velocity and acceleration related,

I CAN identify all forces acting on objects in

motion or at rest.

I CAN explain the advantages of using each of

the six simple machines to do work.

I CAN predict changes in gravitational force as

a result of changes in mass and/or distance.

3.
Essential Question:

• What is the relationship between

velocity and acceleration?

Supporting Questions:

• How can motion of an object be

determined by a graph?

• What is the relationship between

velocity and acceleration?

Supporting Questions:

• How can motion of an object be

determined by a graph?

4.
Speed, Velocity, and Acceleration

5.
Goals:

• To investigate what is needed to describe

motion completely.

• To compare and contrast speed and

velocity.

• To learn about acceleration.

• To investigate what is needed to describe

motion completely.

• To compare and contrast speed and

velocity.

• To learn about acceleration.

6.
To describe motion accurately and completely, a frame of reference is needed.

7.
An object is in motion if it changes

position relative to a reference point.

• Objects that we call stationary—such as a

tree, a sign, or a building—make good

reference points.

The passenger can use a tree as a reference point to decide if the

train is moving. A tree makes a good reference point because it is

stationary from the passenger’s point of view.

position relative to a reference point.

• Objects that we call stationary—such as a

tree, a sign, or a building—make good

reference points.

The passenger can use a tree as a reference point to decide if the

train is moving. A tree makes a good reference point because it is

stationary from the passenger’s point of view.

8.
Describing Motion

Whether or not an

object is in motion

depends on the

reference point

you choose.

Whether or not an

object is in motion

depends on the

reference point

you choose.

9.
Distance

When an object moves, it goes from point

A to point B – that is the DISTANCE it

traveled. (SI unit is the meter)

Distance is how much ground an object has

covered during its motion.

B A

When an object moves, it goes from point

A to point B – that is the DISTANCE it

traveled. (SI unit is the meter)

Distance is how much ground an object has

covered during its motion.

B A

10.
Displacement

Knowing how far something moves is not sufficient. You

must also know in what direction the object moved.

Displacement is how

far our of place the

object is; it is the

object’s overall

change in position.

Knowing how far something moves is not sufficient. You

must also know in what direction the object moved.

Displacement is how

far our of place the

object is; it is the

object’s overall

change in position.

11.
• It is a rate!

• What does that

mean?

• A change over time.

What is the change?

• Change in position, in

other words, distance.

• Standard unit: meters

per second (m/s)

• What does that

mean?

• A change over time.

What is the change?

• Change in position, in

other words, distance.

• Standard unit: meters

per second (m/s)

12.
• Average speed – rate • v = d/t

for the duration of an • v – velocity

entire trip • d – distance

• This can be • t – time

calculated…ready for

• What units do we

the equation?

use?

• Try the practice

problems.

for the duration of an • v – velocity

entire trip • d – distance

• This can be • t – time

calculated…ready for

• What units do we

the equation?

use?

• Try the practice

problems.

13.
Speed

Calculating Speed: If you know the distance an

object travels in a certain amount of time, you

can calculate the speed of the object.

What is

instantaneous

speed?

Instantaneous

speed is the

velocity of an

object at a

certain time.

Speed = Distance/time Average speed = Total distance/Total time

Calculating Speed: If you know the distance an

object travels in a certain amount of time, you

can calculate the speed of the object.

What is

instantaneous

speed?

Instantaneous

speed is the

velocity of an

object at a

certain time.

Speed = Distance/time Average speed = Total distance/Total time

14.

15.
Describing

Describing Motion

Motion

Velocity

Because velocity depends on direction as well

as speed, the velocity of an object can

change even if the speed of the object

remains constant.

The speed of this car

might be constant,

but its velocity is not

constant because the

direction of motion

is always changing.

Describing Motion

Motion

Velocity

Because velocity depends on direction as well

as speed, the velocity of an object can

change even if the speed of the object

remains constant.

The speed of this car

might be constant,

but its velocity is not

constant because the

direction of motion

is always changing.

16.
Velocity

Velocity is a description of an object’s

speed and direction.

As the sailboat’s direction

changes, its velocity also

changes, even if its speed stays

the same. If the sailboat slows

down at the same time that it

changes direction, how will its

velocity be changed?

Velocity is a description of an object’s

speed and direction.

As the sailboat’s direction

changes, its velocity also

changes, even if its speed stays

the same. If the sailboat slows

down at the same time that it

changes direction, how will its

velocity be changed?

17.
Speed v. Velocity

1. How are speed and velocity similar?

They both measure how fast something is moving

2. How are speed and velocity different?

Velocity includes the direction of motion and

speed does not (the car is moving 5mph East)

3. Is velocity more like distance or

displacement? Why?

Displacement, because it includes direction.

1. How are speed and velocity similar?

They both measure how fast something is moving

2. How are speed and velocity different?

Velocity includes the direction of motion and

speed does not (the car is moving 5mph East)

3. Is velocity more like distance or

displacement? Why?

Displacement, because it includes direction.

18.
Graphing Speed

Speed

T increasing

Object begins moving at

a different speed

Object is

C stopped

TIME

Speed

T increasing

Object begins moving at

a different speed

Object is

C stopped

TIME

19.
The steepness of a line on a graph is called

slope.

• The steeper the slope is, the greater the

speed.

• A constant slope represents motion at

constant speed.

Using the points shown, the rise is

400 meters and the run is 2 minutes.

To find the slope, you divide

400 meters by 2 minutes. The slope is

200 meters per minute.

slope.

• The steeper the slope is, the greater the

speed.

• A constant slope represents motion at

constant speed.

Using the points shown, the rise is

400 meters and the run is 2 minutes.

To find the slope, you divide

400 meters by 2 minutes. The slope is

200 meters per minute.

20.
Formula for Calculating Speed

Speed = Distance time

Speed = Distance time

21.
Problem Solving: Calculating

Speed

What is the speed of a sailboat that is traveling 120 meters in 60 seconds?

Step 1: Decide what the problem is asking? A boat traveled 120 meters in 60

seconds. What was the speed of the boat?

Step 2: What is the formula to calculate speed? Speed = Distance/Time

Step 3: Solve the problem using the formula:

Speed = 120 meters 60 seconds = 2 m/s

So, the boat was traveling at 2 m/s

Now you try:

What is the speed of a car that is traveling 150

miles in 3 hours?

Speed

What is the speed of a sailboat that is traveling 120 meters in 60 seconds?

Step 1: Decide what the problem is asking? A boat traveled 120 meters in 60

seconds. What was the speed of the boat?

Step 2: What is the formula to calculate speed? Speed = Distance/Time

Step 3: Solve the problem using the formula:

Speed = 120 meters 60 seconds = 2 m/s

So, the boat was traveling at 2 m/s

Now you try:

What is the speed of a car that is traveling 150

miles in 3 hours?

22.
Answer:

Step 1: What are the facts in the problem?

A car is traveling 150 miles in 3 hours.

Step 2: What is the formula to solve the

problem? Speed = Distance/Time

Step 3: Solve the problem.

Speed = 150 miles 3 hours

Speed = 50 miles/hr.

So, the car is traveling 50 miles/hr.

Step 1: What are the facts in the problem?

A car is traveling 150 miles in 3 hours.

Step 2: What is the formula to solve the

problem? Speed = Distance/Time

Step 3: Solve the problem.

Speed = 150 miles 3 hours

Speed = 50 miles/hr.

So, the car is traveling 50 miles/hr.

23.
Acceleration

Acceleration is the rate at which velocity

changes.

Acceleration can result from a change in

speed (increase or decrease), a change

in direction (back, forth, up, down left,

right), or changes in both.

Acceleration is the rate at which velocity

changes.

Acceleration can result from a change in

speed (increase or decrease), a change

in direction (back, forth, up, down left,

right), or changes in both.

24.

25.

26.

27.

28.
• The pitcher throws. The ball speeds toward the

batter. Off the bat it goes. It’s going, going, gone! A

home run!

• Before landing, the ball went through several changes

in motion. It sped up in the pitcher’s hand, and lost

speed as it traveled toward the batter. The ball

stopped when it hit the bat, changed direction, sped

up again, and eventually slowed down. Most examples

of motion involve similar changes. In fact, rarely does

any object’s motion stay the same for very long.

batter. Off the bat it goes. It’s going, going, gone! A

home run!

• Before landing, the ball went through several changes

in motion. It sped up in the pitcher’s hand, and lost

speed as it traveled toward the batter. The ball

stopped when it hit the bat, changed direction, sped

up again, and eventually slowed down. Most examples

of motion involve similar changes. In fact, rarely does

any object’s motion stay the same for very long.

29.
Understanding Acceleration

1. As the ball falls from the girl’s hand, how does its

speed change?

2. What happens to the speed of

the ball as it rises from the ground

back to her hand?

3. At what point does the ball

have zero velocity? When it

stops and has no direction.

4. How does the velocity

of the ball change when

it bounces on the floor?

1. As the ball falls from the girl’s hand, how does its

speed change?

2. What happens to the speed of

the ball as it rises from the ground

back to her hand?

3. At what point does the ball

have zero velocity? When it

stops and has no direction.

4. How does the velocity

of the ball change when

it bounces on the floor?

30.
You can feel acceleration!

If you’re moving at 500mph

east without turbulence,

there is no acceleration.

But if the plane hits an air pocket and drops 500 feet

in 2 seconds, there is a large change in acceleration and

you will feel that!

It does not matter whether you speed up or

slow down; it is still considered a change in

acceleration.

If you’re moving at 500mph

east without turbulence,

there is no acceleration.

But if the plane hits an air pocket and drops 500 feet

in 2 seconds, there is a large change in acceleration and

you will feel that!

It does not matter whether you speed up or

slow down; it is still considered a change in

acceleration.

31.
In science, acceleration refers to increasing speed,

decreasing speed, or changing direction.

• A car that begins to move from a stopped position or speeds

up to pass another car is accelerating.

• A car decelerates when it stops at a red light. A water skier

decelerates when the boat stops pulling.

• A softball accelerates when it changes direction as it is hit.

decreasing speed, or changing direction.

• A car that begins to move from a stopped position or speeds

up to pass another car is accelerating.

• A car decelerates when it stops at a red light. A water skier

decelerates when the boat stops pulling.

• A softball accelerates when it changes direction as it is hit.

32.
Calculating Acceleration

Acceleration = Change in velocity

Total time

So…Acceleration = (Final speed – Initial speed)

Time

Acceleration = Change in velocity

Total time

So…Acceleration = (Final speed – Initial speed)

Time

33.
Calculating Acceleration

As a roller-coaster car starts down a slope, its

speed is 4 m/s. But 3 seconds later, at the

bottom, its speed is 22 m/s. What is its

average acceleration?

What information have you

been given?

Initial speed = 4 m/s

Final Speed = 22 m/s

Time = 3 s

As a roller-coaster car starts down a slope, its

speed is 4 m/s. But 3 seconds later, at the

bottom, its speed is 22 m/s. What is its

average acceleration?

What information have you

been given?

Initial speed = 4 m/s

Final Speed = 22 m/s

Time = 3 s

34.
Calculating Acceleration

What quantity are you trying to calculate?

The average acceleration of the roller-coaster car.

What formula contains the given quantities and the

unknown quantity?

Acceleration = (Final speed – Initial speed)/Time

Perform the calculation.

Acceleration = (22 m/s – 4 m/s)/3 s = 18 m/s/3 s

Acceleration = 6 m/s2

The roller-coaster car’s average acceleration is 6 m/s2.

What quantity are you trying to calculate?

The average acceleration of the roller-coaster car.

What formula contains the given quantities and the

unknown quantity?

Acceleration = (Final speed – Initial speed)/Time

Perform the calculation.

Acceleration = (22 m/s – 4 m/s)/3 s = 18 m/s/3 s

Acceleration = 6 m/s2

The roller-coaster car’s average acceleration is 6 m/s2.

35.
Graphing acceleration

Object

E accele-

rates Object decelerates

D Object moves

at constant

speed

Time

Object

E accele-

rates Object decelerates

D Object moves

at constant

speed

Time

36.
Now You Try:

A roller coasters velocity at the top

of the hill is 10 m/s. Two seconds

later it reaches the bottom of the hill

with a velocity of 26 m/s. What is

the acceleration of the coaster?

A roller coasters velocity at the top

of the hill is 10 m/s. Two seconds

later it reaches the bottom of the hill

with a velocity of 26 m/s. What is

the acceleration of the coaster?

37.
The slanted, straight line on this speed-versus-time graph tells you that

the cyclist is accelerating at a constant rate. The slope of a speed-

versus-time graph tells you the object’s acceleration. Predicting How

would the slope of the graph change if the cyclist were accelerating at a

greater rate? At a lesser rate?

the cyclist is accelerating at a constant rate. The slope of a speed-

versus-time graph tells you the object’s acceleration. Predicting How

would the slope of the graph change if the cyclist were accelerating at a

greater rate? At a lesser rate?

38.
Since the slope is increasing, you can conclude that the

speed is also increasing. You are accelerating.

Distance-Versus-

Time Graph The

curved line on this

distance-versus-time

graph tells you that

the cyclist is

accelerating.

speed is also increasing. You are accelerating.

Distance-Versus-

Time Graph The

curved line on this

distance-versus-time

graph tells you that

the cyclist is

accelerating.

39.
Acceleration Problems

A roller coaster is moving at 25 m/s at the

bottom of a hill. Three seconds later it reaches

the top of the hill moving at 10 m/s. What was

the acceleration of the coaster?

Initial Speed = 25 m/s

Final Speed = 10 m/s

Time = 3 seconds

Remember (final speed – initial speed) ÷ time is acceleration.

(10 m/s – 25 m/s) ÷ 3 s = -15 m/s ÷ 3 s = -5 m/s2

This roller coaster is decelerating.

A roller coaster is moving at 25 m/s at the

bottom of a hill. Three seconds later it reaches

the top of the hill moving at 10 m/s. What was

the acceleration of the coaster?

Initial Speed = 25 m/s

Final Speed = 10 m/s

Time = 3 seconds

Remember (final speed – initial speed) ÷ time is acceleration.

(10 m/s – 25 m/s) ÷ 3 s = -15 m/s ÷ 3 s = -5 m/s2

This roller coaster is decelerating.

40.
A car’s velocity changes from 0 m/s to 30

m/s in 10 seconds. Calculate acceleration.

Final speed = 30 m/s

Initial speed = 0 m/s

Time = 10 s

Remember (final speed – initial speed) ÷ time is acceleration.

(30 m/s – 0 m/s) ÷ 10 s = 30 m/s ÷ 10 s = 3 m/s2

m/s in 10 seconds. Calculate acceleration.

Final speed = 30 m/s

Initial speed = 0 m/s

Time = 10 s

Remember (final speed – initial speed) ÷ time is acceleration.

(30 m/s – 0 m/s) ÷ 10 s = 30 m/s ÷ 10 s = 3 m/s2

41.
A satellite’s original velocity is 10,000 m/s.

After 60 seconds it s going 5,000 m/s. What is

the acceleration?

Remember (final speed – initial speed) ÷ time is acceleration.

Final speed (velocity) = 5000 m/s

Initial speed (velocity) = 10,000 m/s

Time = 60 seconds

(5000 m/s – 10,000 m/s) ÷ 60 s = -5000 m/s ÷ 60 s

= -83.33 m/s2

**This satellite is decelerating.

After 60 seconds it s going 5,000 m/s. What is

the acceleration?

Remember (final speed – initial speed) ÷ time is acceleration.

Final speed (velocity) = 5000 m/s

Initial speed (velocity) = 10,000 m/s

Time = 60 seconds

(5000 m/s – 10,000 m/s) ÷ 60 s = -5000 m/s ÷ 60 s

= -83.33 m/s2

**This satellite is decelerating.

42.
• If a speeding train hits the brakes and it

takes the train 39 seconds to go from 54.8

m/s to 12 m/s what is the acceleration?

Remember (final speed – initial speed) ÷ time is acceleration.

Final speed= 12 m/s

Initial speed= 54.8 m/s

Time = 39 s

12 m/s – 54.8 m/s ÷ 39 s = -42.8 m/s ÷ 39 s

= -1.097 m/s2

This train is decelerating.

takes the train 39 seconds to go from 54.8

m/s to 12 m/s what is the acceleration?

Remember (final speed – initial speed) ÷ time is acceleration.

Final speed= 12 m/s

Initial speed= 54.8 m/s

Time = 39 s

12 m/s – 54.8 m/s ÷ 39 s = -42.8 m/s ÷ 39 s

= -1.097 m/s2

This train is decelerating.