Center of Mass

Welcome back! Today we talked about the center of mass: what it is, how to find it, and some cool things we can do with it.

Notes: Center of Mass

Your book does not have many problems involving only the center of mass, so I had to make up problems. Your homework is:

1.A uniform meter stick has a mass of 0.20kg.

a)Where is its center of mass?

b)A 0.30 kg mass is taped to the meter stick at the 80 cm mark. Now where is the COM of the system?

2. A young girl of mass 35 kg is 4.0 meters from the shore of a lake, standing at one end of a uniform raft of mass 90. kg and length 3.0 m. She walks along the raft away from the shore until she gets to the other end of the raft. How far is she from the shore now?

Also, a few of you asked for the address of the planets simulation some classes looked at:
My Solar System

Next class you will also be completing a small lab, so bring your lab notebook.

Center of Mass

Welcome back! Today we talked about the center of mass: what it is, how to find it, and some cool things we can do with it.

Notes: Center of Mass

Your book does not have many problems involving only the center of mass, so I had to make up problems. Your homework is:

1.A uniform meter stick has a mass of 0.20kg.

a)Where is its center of mass?

b)A 0.30 kg mass is taped to the meter stick at the 80 cm mark. Now where is the COM of the system?

2. A young girl of mass 35 kg is 4.0 meters from the shore of a lake, standing at one end of a uniform raft of mass 90. kg and length 3.0 m. She walks along the raft away from the shore until she gets to the other end of the raft. How far is she from the shore now?

Also, a few of you asked for the address of the planets simulation some classes looked at:
My Solar System

Next class you will also be completing a small lab, so bring your lab notebook.

More on Rotational Inertia

Yesterday we defined and practiced finding the rotational inertia for point masses. Today we talked about the rotational inertia of extended objects such at rods, spheres, and disks.

Notes: More on Rotational Inertia

Homework: p.269 #33 & 39

Center of Mass

Welcome back! Today we talked about the center of mass: what it is, how to find it, and some cool things we can do with it.

Notes: Center of Mass

We also completed this short qualitative lab:

Choose at least 3 different cardboard pieces. Sketch them in your lab notebook and qualitatively find their centers of mass. Write a brief description of your procedure and mark the COM on your sketches in your notebook.

Your book does not have many problems involving only the center of mass, so I had to make up a problem. Your homework is:

1.A uniform meter stick has a mass of 0.20kg.

a)Where is its center of mass?

b)A 0.30 kg mass is taped to the meter stick at the 80 cm mark. Now where is the COM of the system?

2. A young girl of mass 35 kg is 4.0 meters from the shore of a lake, standing at one end of a uniform raft of mass 90. kg and length 3.0 m. She walks along the raft away from the shore until she gets to the other end of the raft. How far is she from the shore now?

Also, a few of you asked for the address of the planets simulation some classes looked at:
My Solar System

Next class you will also be completing a small lab, so bring your lab notebook.

Center of Mass

Welcome back! Today we talked about the center of mass: what it is, how to find it, and some cool things we can do with it.

Notes: Center of Mass

We also completed this short qualitative lab:

Choose at least 3 different cardboard pieces. Sketch them in your lab notebook and qualitatively find their centers of mass. Write a brief description of your procedure and mark the COM on your sketches in your notebook.

Your book does not have many problems involving only the center of mass, so I had to make up problems. Your homework is:

1.A uniform meter stick has a mass of 0.20kg.

a)Where is its center of mass?

b)A 0.30 kg mass is taped to the meter stick at the 80 cm mark. Now where is the COM of the system?
2. A young girl of mass 35 kg is 4.0 meters from the shore of a lake, standing at one end of a uniform raft of mass 90. kg and length 3.0 m. She walks along the raft away from the shore until she gets to the other end of the raft. How far is she from the shore now?

Also, a few of you asked for the address of the planets simulation some classes looked at:
My Solar System

Practice Test

Your test for this unit will be on Thursday. Wednesday will probably be totally eaten up by the Senior Debates, so today is your day to study for your test.

Rotational Dynamics Test Practice

Abridged answers

I also have some videos, but they are for an older version and some of the problems have changed.

#4
#5
#7 (PART C HAS CHANGED)
#8
#9 (energy method), #9 (dynamics method) (THIS HAS CHANGED)
#10
#11 (THIS HAS CHANGED)

Practice and Mobile Turn-In

Your mobile projects are due today! Because needed class time to check mobiles, you spent the period practicing some problems that cover everything we've done so far this unit. We have two more topics to cover starting tomorrow, so this serves as a way to cement what we've learned so far.

The test this unit is currently scheduled for next Thursday, January 28th (the day after senior debates).

If you didn't finish the practice problems in class, they are homework:

Chapter 8 (p.263) CONCEPTUAL #6 & 12, + PROBLEMS (p. 268) #30, 70, 74, 78

Center of Mass

Welcome back! Today we talked about the center of mass: what it is, how to find it, and some cool things we can do with it.

Notes: Center of Mass

We also completed this short qualitative lab:

Choose at least 3 different cardboard pieces. Sketch them in your lab notebook and qualitatively find their centers of mass. Write a brief description of your procedure and mark the COM on your sketches in your notebook.

Your book does not have many problems involving only the center of mass, so I had to make up a problem. Your homework is:

1.A uniform meter stick has a mass of 0.20kg.

a)Where is its center of mass?

b)A 0.30 kg mass is taped to the meter stick at the 80 cm mark. Now where is the COM of the system?

+Ch.8 (p. 272) # 69

Also, a few of you asked for the address of the planets simulation some classes looked at:
My Solar System

Chapter 8 Practice Exam

Your exam for chapter 8 will be on Thursday. Wednesday will probably be totally eaten up by the Debates, so today is your day to study for your exam. I have a practice exam for you and I will post solutions videos tonight.

Ch. 8 Practice Exam (the formatting on the pictures is a bit messed up in Google Docs. You can also try this link)

Solutions Videos:

#4
#5
#7
#8
#9 (energy method), #9 (dynamics method)
#10
#11

Don't want to watch all of the solutions videos? I have a key with just the answers here.

Cool Video From Oshadha

Oshadha found a great video that talks about using the concepts of mass and moment of inertia in toy 3D printing. Check it out!

3D Printing: the Physics of Objects

More on Moment of Inertia

Yesterday we defined and practiced finding the moment of inertia for point masses. Today we talked about the moment of inertia of extended objects such at rods, spheres, and disks.

Notes: More on Moment of Inertia

Homework tonight is Ch. 8 (p.269 ) #33 & 39

Center of Mass

Welcome back! Today we talked about the center of mass: what it is, how to find it, and some cool things we can do with it.

Notes: Center of Mass

We also completed this short qualitative lab:

Choose at least 3 different cardboard pieces. Sketch them in your lab notebook and qualitatively find their centers of mass. Write a brief description of your procedure and mark the COM on your sketches in your notebook.

Your book does not have many problems involving only the center of mass, so I had to make up a problem. Your homework is:

1.A uniform meter stick has a mass of 0.20kg.

a)Where is its center of mass?

b)A 0.30 kg mass is taped to the meter stick at the 80 cm mark. Now where is the COM of the system?

+Ch.8 (p. 272) # 69

Also, a few of you asked for the address of the planets simulation some classes looked at:
My Solar System