**Interactive Study Links**

• Create an account and make your own flashcards at Quizlet.com!

**Other Study Links**

• Several links to various worksheets at Debbie's Educator's Resources.

*(Thanks, Debbie!)*

**(1) p. 205-207a, Mechanics - The Study of Motion**

All motion is relative to a reference point.

**(2) p. 207-209, Speed: How Quickly Motion Occurs**

Review of Converting Units - Simple but Great!

speed = distance/time

Converting Units (for example, from miles to meters, or hours to seconds, etc.)

**(3) p. 209-214, Velocity: Speed and Direction**

Vector Quantities and Scalar Quantities

Velocity has speed

*and*direction

0:00-2:35 from this video.

Relative Velocity

2:55-end from this video.

**(4) p. 214-220, Acceleration: The Change in Velocity**

What is acceleration?

Finding the rate of acceleration:

Acceleration =

__final velocity - initial velocity__

time

Your answer will have something like

**feet/second²**or

**miles/hour²**and

**. Acceleration always is in a direction.**

__will need to include a direction__►

**Note**that Example 9.3 and the

*1st example*in Example 9.4 are of

**objects that are falling.**

The

*2nd example*in 9.4 is not. (It is of an object that is slowing down.) Nor is the example in 9.5.

These are all in the same section in your textbook, so just be aware that the same formula (for acceleration) will give

**varied**answers for objects that are

**not**falling, and the

**same**answer every time for objects that

**are**falling.

See the statement below. ↓

**"The acceleration**

__due to gravity__for any object is 9.8 meters/second² in metric units and 32 feet/second² in English units."*-Apologia Physical Science, 1st edition, p. 223*

*(Lol, that must have been one strong little girl!)*

So... what is this

*per second, per second*thing?

__32 feet__

__sec__

sec ←This is read as "32 feet per second, per second."

It is usually then written as 32 feet/sec².

*But what does it mean???*

It means that each second an object is falling, it increases speed by an additional 32 feet per second.

Like this: 32, 64, 96, 128, 160... etc.

But this is only UNTIL the downward pull of gravity and the upward push of air resistance is equal.

Then the object will begin to fall at a consistent speed.

This is like Example 9.5

I like how he converts more than one type of unit, but uses fewer steps than in our book.

See Example 9.4

**B**

The next-to-last sentence on p. 217 of the first edition of Apologia Physical Science says,

*"If it is slowing down, its acceleration is in the opposite direction as its velocity."*

If you do the math, you will get a negative answer.

So if you are driving east and slowing down, your acceleration would be written as west.

If you were driving north and slowing down, and calculated your velocity to be -15 m/s², you would write it as 15 m/s² south. (no negative and the direction is changed)

**►Note:**Acceleration is a change in velocity. If you are going at a

__constant__velocity (not changing speed), there is

__no acceleration__. You would say your acceleration is

__zero__.

Abbreviations of units

0:00-3:35 from this video. Also see the awesome Triangle Trick from 9:20-10:45! =)

speed = distance/time.

distance = speed x time

time = distance/speed

**(5) p. 220-226, The Acceleration Due to Gravity**

Low Gravity.

Objects fall at the same rate in the absence of air resistance.

**Physics of Skydiving**

You learned about the acceleration of objects as they fall.

Falling objects will accelerate UNTIL the downward pull of gravity and the upward push of air resistance is equal, as when a skydiver falls (as long as he holds his body position the same). Then he will begin to fall at a consistent speed.

**Gravity on Falling Objects**

The pull of gravity is stronger on a heavier object, true, but inertia equals that out. (Inertia means that objects stay where they are unless acted on by an outside force.) So heavier objects will not fall faster than lighter objects.

I have been unable to find a video for the formula for

**finding distance for an object in free fall**.

You'll just have to read the directions in the textbook and follow the formula carefully.

distance = ½ • acceleration • (time)²

Don't forget to square the time unit.

And use the correct acceleration formula, whether feet or meters.

**"The acceleration**

__due to gravity__for any object is 9.8 meters/second² in metric units and 32 feet/second² in English units."*-Apologia Physical Science, 1st edition, p. 223*

Reviewing Conversions - using fewer steps.

Thanks for this wonderful blog! It's been a blessing to us, and I think it will continue to be as the year progresses.

ReplyDeleteGod bless

You're welcome!

ReplyDeleteI'm glad it has been a help to you. =)

What a huge help this is- thank you for sharing these great resources! I'm not sure who's learning more- my son or myself. Either way, it's a good thing. :)

ReplyDeleteI felt the same way! I learned a ton last year. =D

ReplyDeleteGlad you're finding it helpful.

Doing Biology now, and I can't decide which I like better.

Thank you so much for collecting these videos! Found your website yesterday in desperation as module 9 Physics is tough for my kids to grasp...made things so much easier today and they had fun watching.

ReplyDeleteYou're welcome! Glad it helped. =)

DeleteThank you Marty. Physics is greek to me and having all this help in one spot is terrific.

ReplyDeleteYou're welcome, Dianna! =)

DeleteI am a student and I have taken the test that covers acceleration, velocity, speed,etc. I have failed both times I have taken the test. After watching this it is going to be an easy A! Thank you so much for your help! God Bless You!

ReplyDeleteYou're welcome! Come back and tell me how you did on your test. =)

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