Extra Recording

Hi folks,

The second recording I sent was for my Earth Science class.  It defaulted to the wrong email address.  Sorry about that.  However, if you want a atomic structure refresher…please enjoy!  :)

Best,

Jim Mueller

(919) 907-3217

Recording of 10/29 Physics Class - 2 Dimensional Motion

https://youtu.be/hELtSoUqfkk

10/29 Physics Class and homework due 11/5

Hi folks,

Today we spent time going over some of our previous problems and trying to make sure everyone is on the right track.

For homework, I want you to predict how far an object would go (d horizontal )  if it's shot parallel to the ground at the following heights and speeds.  Feel free to review your notes on this before you start.  Use d = 1/2 at^2 to find time.   Then use that time to find distance by using v=d/t.  (Use v=d/t to find horizontal distance travelled since there is NO acceleration horizontally.)

1.  5 m high  5 m/s

2.  10 m high  5 m/s

3.  15 m high 5m/s

4.  10 m high 10 m/s

5.  15 m high 30 m/s

Now, once you've done those calculations go to this website. https://phet.colorado.edu/en/simulation/projectile-motion.  When you get there click on the play triangle and then click "Intro".

Now use the website to see if your calculations are correct.  Set the appropriate velocities and heights and see if your calculations match the simulation. You can adjust the height by clicking and dragging on the tower the cannon is sitting on.  Be sure the cannon is shot at 0 degrees.  You can move the "target" to see the distance it traveled.  You can also use the measuring tape and/or the blue box that are located at the top middle of the screen.  Your calculations should be close to the results.  If not…check your math.

6.  Did your calculation match the sim?

7.  Put the initial speed to 0m/s.  Do the times still match the times you calculated for the different heights?  (Hint: they should.)

Under "Velocity Vectors" to the right, click on  "components" .

Shoot the cannon parallel to the ground (0 degrees).  You may want to put this on slow and feel free to pause the sim as the cannon ball is moving.

6.  As the pumpkin flies through the air, describe how the vertical velocity vector changes?

7.  As the pumpkin flies through the air, describe how the horizontal vector changes?

Now, turn on the "total" in the velocity vector box.  Pause the simulation as the pumpkin flies.  Notice carefully how the resultant velocity is a combination of the vertical and horizontal velocities.

Now shoot the cannon upwards at an angle of 60 degrees.

8.  As the pumpkin flies through the air, describe how the vertical velocity vector changes?

9.  As the pumpkin flies through the air, describe how the horizontal vector changes?

Typo/error in the answers for the 10/29 Homework assignment

In question #3c I should have used 7 seconds instead of 6. So the answer should be:

v=d/t
v= 76/7
v= 10.9 m/s

Sorry about that folks.

Jim Mueller

10/22 Class recording and recording of the Ball Throwing Math

https://youtu.be/DhjBtjUYu3Q  Class Recording

https://youtu.be/g5b1kYxZv0g  Math of the Ball Throw

10/22 HS Physics update and homework due 10/29

Hi folks,

This week we covered gravity in a bit more detail and spent some time exploring gravity in relation to our acceleration and velocity formulas we've been working on.  To do this, we went outside and everyone got a chance to throw a ball as far and as high as they could.  We then calculated the height, the vertical velocity and the horizontal velocity of the throw.

For homework this week:

Read pages 168 - 179 in the Conceptual Physics book.

Do Review Questions 1 - 14 on page 180.

Also, calculate the answers to the following questions using the formulas we used today.  Also, we are in Newtonia so don't worry about air resistance.  :) 

1.  Using the first dive on this video https://youtu.be/ttetLjQ4du8?t=81

a.  If the platform is 30 m high, how long does it take him to hit the water?

b.  How fast is he going when he hits the water?  (Use the time you found from the first question)

2. Use the first drop from this video https://youtu.be/-6h65t2MOfU?t=286

a.  If the dam is 165 m high, how long does it take the ball to hit the ground?

b. How fast is the ball falling when it hits the ground?

3.  Use the first hit on this video video https://youtu.be/rojPcO_LwvM?t=49  The ball is in the air for 7 seconds.

a.  How high is this ball hit?  (Remember to 1/2 your time.  It goes up for half the time and comes down for half)

b.  What was the vertical speed of the hit?

c.  If that ball flew 76 m (about 250 ft) what was the horizontal speed of the ball?

4. Use the first throw on this video https://youtu.be/n5ctPAqt_wk?t=14  Assume the ball was in the air for 3 seconds.

a. How high does this ball go?

b. How fast is the vertical speed?

c. How fast is the horizontal speed if the throw was 70 m (about 230 ft)

5.  Use the first punt on this video https://www.youtube.com/watch?v=OtP1eRKW9PI  The ball is in the air for 6 seconds.

a.  a. How high does this ball go?

b. How fast is the vertical speed?

c. How fast is the horizontal speed if the punt was 82 m (about 91 yards)

Answers:

1.

a.)  d = 1/2at^2  

 30 = 1/2 10 t^2

 30 = 5 t^2

 6 = t^2

 2.5s = t

b). v= at

v = 10 x 2.5

v = 25 m/s about 56 mph!!!

2. 

a) d = 1/2at^2  

165m = 1/2 10 t^2

165 = 5 t^2

33 = t^2

5.7 s = t

b) v = at

 v = 10 x 5.7

 v = 57 m/s about 128 mph!!!!!

 3. Remember to half the time for the calculations since half the time was going up and the other half down.

a.)  d = 1/2 at^2

   d = 1/2 10 x 3.5^2

   d = 5 x 12.3

   d = 61.5 m about 202 ft

b ) v = at

     v = 10 x 3.5

     v = 35 m/s  or 115 mph

c) v = d/t

   v = 76 / 6   Use the full 6 seconds here because it did take the ball 6 seconds to travel that 76 m.

   v = 12.7 m/s  about 28 mph

 

4.  Remember to half the time for the calculations since half the time was going up and the other half down.

a) d = 1/2 at^2

    d = 1/2 10 x 1.5^2

   d = 5 x 2.25

   d = 11.25 m about 37 ft

b) v = at

   v = 10 x 1.5

   v = 15 m/s about 33 mph

c) v = d/t

    v = 70/3   Use the full time here.

   v = 23.3 m/s about 52 mph !!

5. Remember to half the time for the calculations since half the time was going up and the other half down.

a. d = 1/2 gt^2    

d = 1/2 x 10 x 3^2   

d = 5 x 9

d = 45 m  about 144 ft

b. v = at

v = 10 x 3

v = 30 m/s  about 67 mph!

c. v = d/t

v = 82 / 6  Use the full time here.

v = 13. 7 m/s  about 31 mph

10/15 Physics update and homework due 10/22

Hi folks,

Today we spent a good amount of time tackling those velocity and acceleration problems from even more angles.

For homework this week I'd like you to take a look at the following websites and have some fun with the interactives. 

For this link, get at least 8 stars.  These take some time to get used to but with some trial and error you should be able to get the hang of them.  I found the Speed v. Time Graphs to be a bit easier than the Distance vs. Time ones. When you are done take a picture or a screen shot to show me that you've done the assignment.   Graphs and Ramps Interactive

For this link, do all the "Apprentice Level" and all the "Master Level" problems.  Again, take a screen shot or a picture when you're done.  That Motion Concept Builder

Have fun!

10/15 HS Physics - Working more problems

https://youtu.be/igp7wbndZuY

10/8 Physics Recording - Acceleration Graphs

https://youtu.be/Fhf4R5CfgBk

10/8 Physics Class update and homework due 10/15

Hi folks,

Got into some of the serious nitty gritty of velocity, distance and acceleration graphs today.

For homework this week:

On page 26 do all the Plug and Chug questions. I've included the answers in a photo below.

On page 27 do all the Think and Explain questions

Also do questions 1 - 5 in the enclosed document.

Best,

Jim Mueller

(919) 907-3217

10/1 Physics Recording - Acceleration

https://youtu.be/WpgYOJnHYK0

10/1 Physics class update and homework due 10/8

Hi folks,

Today we spent some time getting to know the concept of acceleration. It's a key concept in physics and one we will be working with quite a bit and coming back to a lot over the year.  Most of today was spent on a lab working with the acceleration of rubber band powered vehicles.

Homework for this week will be to work with the data we collected in class to create some graphs and to use those graphs to answer some questions.

To help with this, please watch this video.  It's me explaining how to calculate the data for the graph.

First off, using only your group's data, create two different graphs. (Please use graph paper.)  One for velocity vs. time and one for acceleration vs. time.  Time should always be on the horizontal axis.  

Once you finish your graphs, answer the following questions.

1.  What was the greatest acceleration that you saw overall?


2.  What was the smallest acceleration?


3.  When you saw a negative acceleration, what did that mean the car was doing?


4.  What was the highest speed any of the cars achieved?


5.  If a car has a constant positive acceleration, what is the car continuing to do?


6.  If a car has no acceleration what is the car continuing to do? 


7. Draw 2 more graphs (one for velocity and one for acceleration) but this time, try to image what the graphs would have looked like in a perfect world.  In other words, if the cars had a nice steady acceleration at the beginning and at the end of their runs.  Think carefully about this.  The acceleration graph may be different than you first think.  

Best,

Jim Mueller

(919) 907-3217