1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
ziro4ka [17]
3 years ago
8

A disk rotates freely on a vertical axis with an angular velocity of 30 rpm. An identical disk rotates above it in the same dire

ction about the same axis, but without touching the lower disk, at 20 rpm. The upper disk then drops onto the lower disk. After a short time, because of friction, they rotate together. The final angular velocity of the disks is
A. 50 rpm
B. 40 rpm
C. 25 rpm
D. 20 rpm
E. 10 rpm
Physics
1 answer:
weqwewe [10]3 years ago
8 0

Answer:

c. 25 rpm

Explanation:

The inertia of both disk is the same so

I_1=I_2

I_1*w_{1i}+I_2*w_{2i}=I_1*w_{1f}+I_2*w_{2f}

I*(w_{1i}+w_{2i})=I*(w_{1f}+w_{2f})

w_{1f}=w_{2f}=w_f

w_{1f}+w_{2f}=2w_f

w_f=\frac{w_{1i}+w_{i2}}{2}

w_f=\frac{30rpm+20rpm}{2}

w_f=\frac{50rpm}{2}

w_f=25rpm

You might be interested in
- What do the objects not in motion have in common?​
Semenov [28]

Answer:

they have zero velocity

Explanation:

8 0
3 years ago
What is the best book for physics practicals??(pdf)
scoray [572]

Answer:

I would strongly recommend Exploring Quantum Physics through Hands-on Projects for physics practicals.

Explanation:

  • Though it is not about books, but it is solely on you how you want to get knowledge. If you are truly passionate about learning physics in a practical way "Exploring Quantum Physics through Hands-on Projects" will be the best one out there.
  • Besides "Laboratory Projects in Physics, a Manual of Practical Experiments for Beginners" is also a promising one.
  • There are detailed chapters on important topics like light as a wave and particles, atoms and radioactivity, Schrödinger, etc.
  • If you wisely follow these books, you will surely get all your doubts cleared and learn new mechanisms easily.
3 0
3 years ago
Hi
Vera_Pavlovna [14]

1) the cotton bolls burst open, and the white cotton fiber can be seen. Ginning: The cotton picked up from the plants has seeds in it. The process of removing cotton seeds from pods is called ginning. Ginning was traditionally done by hand.

2) Preparation

To be used for thread or fabric, raw seed cotton must cleaned and free of debris. Seeds, burrs, dirt, stems and leaf material are removed from the cotton during ginning.

Module feeders break the modules apart and feed the cotton into the gin.

Some module feeders have giant conveyors moving the modules into stationary heads.

Other module feeders are self-propelled, moving down a track alongside the modules.

Once in the cotton gin, the seed cotton moves through dryers and through multiple cleaning machines that remove the gin waste such as burrs, dirt, stems and leaf material from the cotton. Once thoroughly clean and dry, the cotton goes to the gin stand where circular saws with small, sharp teeth pluck the fiber from the seed. This process makes the sliver smoother so more uniform yarns can be produced. Then the cotton is packed tightly into bales, ready to be processed into textiles.

Even though the cotton is cleaned during the ginning process, it's not nearly as clean as  it needs to be. Cotton fibers are shaved from the bales and sent through a series of cleaning and drying machines. The mixed and fluffed-up cotton goes into a carding machine which finishes the cleaning and straightening of the fibers, making them into a soft, untwisted rope called a sliver (pronounced sly-ver).

The sliver is drawn out to a thinner strand and given a slight twist to improve strength, then wound on bobbins (spools wound with the thread-like product for storage).  

It is now called roving and the roving bobbins are now ready for the spinning process.

Spinning

On modern spinning frames, yarn is mare directly from the sliver. The spinning devices take fibers from the sliver and rotate it up to 2,500 revolutions in a second twist that makes fibers into a yarn for weaving or knitting into fabrics.

Spinning is the last process in yarn manufacturing. Today's mills draw and twist the roving into yarn and place it on bobbins. They do this quite efficiently. A large, modern mill can produce enough yarn or thread in 30 days to wrap around the earth 2300 times or go to and return from the moon 235 times. With the use of automatic winding, the yarn bobbins are transferred to larger bobbins called cheese cones. These cheese cones can be stored until they are needed in the weaving process.

Weaving

Looms weave cotton yarns into fabrics the same way the first hand-weaving frames did. Modern looms work at great speeds, interlacing the length-wise yarns (warp) and the crosswise yarns (weft).

Warp refers to yarns that run lengthwise in woven goods. In preparation of warp yarns for weaving, hundreds of yarn strands are wound from cheese cones onto a large warp beam. Yarns on this beam are then coated with a starch mixture (sizing compound) to add strength for weaving.

Weft is the yarn that runs crosswise in woven goods and may be referred to as filling yarn. Sizing is not placed on weft because flexibility is needed in the weaving process.

In today's most modern mills, the weft is fed into the loom from cheese cones with air-jets at such a high speed that its movement cannot be seen.

The woven fabric, called gray goods, is sent to a finishing plant where it is bleached, pre-shrunk, dyed, printed and given a special finish before being made into clothing or products for the home. Other machines make knits for use in shirts, sweaters or blankets.

this website will help you: https://www.quilting-in-america.com/process-of-making-cotton.html

i hope this helps :)

6 0
3 years ago
Which of the following is NOT true about power?
Andrews [41]

Answer:

I think B) is uncorrect

Explanation:

As A) p=w/t so it's correct relation

C) power depend on time and work as work is distance multiple force so it refer to velocity

D) the powerful mean much work in a few time

5 0
2 years ago
On which one of the surfaces listed below will a toy car released with the same initial speed travel the farthest? *
irinina [24]
Are you gonna list the surfaces or nah
5 0
3 years ago
Other questions:
  • How many times did john glenn orbit the earth
    8·1 answer
  • Scientists can estimate the age of a planetary surface by counting __________. scientists can estimate the age of a planetary su
    15·1 answer
  • PLEASE HELP ASAP!!! CORRECT ANSWER ONLY PLEASE!!!
    9·2 answers
  • A black hole in the universe is a An empty region in space b- A massive collapsed star c- A moon that is always turned to its da
    6·1 answer
  • A pulley system has an efficiency of 74.2%. If you perform 200 J of work, how much useful work does the pulley perform?
    13·1 answer
  • If you suspect your system is overheating, how can you determine the cpu temperature?
    6·1 answer
  • What part of the crane is used to lift and lower the load?
    14·2 answers
  • At point A in a Carnot cycle, 2.34 mol of a monatomic ideal gas has a pressure of 1 400 kPa, a volume of 10.0 L, and a temperatu
    6·1 answer
  • Please help with this :(
    6·1 answer
  • What is the displacement of the armadillo between 0s and 24s ?
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!