Difference between solid friction and viscosity is as follows: Viscosity is proportional to the surface area whereas solid friction is independent of area of solid surfaces in contact. Viscous force on the body depends upon its velocity in the viscous media. But, friction does not depend on the velocity of the body.
None I mean you have to take a drivers test but you will have to take the knowldege test twice
Answer:
His journey took him 3 hours 15 minutes.
Explanation: 4 miles every hour. So 1 hr is equal to 4 miles, 2 hrs is equal to 8 miles, 3 hrs is equal to 12 miles. Now he just has 1 miles left, and since it takes him a hour to cycle 4 miles, 60 divided by 4 is 15. Therefore, 1 mile is equal to 15 minutes.
The centre of mass of the system is the point at which the total
mass of system could be concentrated without changing the moment
of the system.
Centre of Mass is the point at which the whole mass of the system
is assumed to be concentrated.
The general formula for the COM is:
xₙ = Σmₐxₐ / Σmₐ where, a = 1,2,3.........n
Here the term Σ mₐ xₐ is called the first moment of the system and the
denominator expression is called total mass of the system.
Therefore, from this theory we can say that the moment of the system
remain unchanged while calculating the COM.
Hence, The centre of mass of the system is the point at which the total
mass of system could be concentrated without changing the moment
of the system.
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85)
The bone structure from outside would be periosteum, cortical, cancellous then medulla. Periosteum is the area outside the bone that will supply nutrition into the outer part of the bone. Cortical is the layer where bone mineral deposition is intense. In this part, the bone is compact and hard. This is the part of the bone that has great strength.
Cancellous is part of the bone where it is not too hard but not too soft. Mineralization is not so dense like cortical layer. That makes this part looks spongy.
In the medulla, most part is made from connective tissue and blood vessels. This part is responsible for the bone vascularization, which means the supply of mineral to the outer part is coming from the medulla. Mineralization is not much in the medulla, makes it not strong. Medulla or marrow also makes blood cells.
86)
The region of the spine would be cervical(neck), thoracal(chest), lumbar(back), sacrum then coccyx. The vertebrae in the neck are smaller since it did not need much strength but need more mobility. Lower part on the thoracal and lumbar is bigger and have a bigger process that will further stabilize the vertebrae. Thoracal vertebrae have a part on their side where the ribs attached. Sacrum shape was a kinda weird because it needs to be able to connect with the pelvis to make buttock. Coccyx the tailbone look like just a small remnant and doesn't seem to have a function in human.
87)
Axis is the name of cervical 2nd vertebral which was located below the atlas, 1st cervical vertebrae. Both of them doesn't have spinal processes that were stabilizing the side of vertebrae Axis also has an odontoid peg which will make the joint with atlas more flexible.
This effect makes the neck can turn to side easily. It also makes neck more mobile vertically, make a nodding movement is possible.
88)
Thre kind of joints would be: Synarthrosis, amphiarthrosis, and diarthrosis.
In synarthrosis, the joint mostly made by fibrous so that it can move. The example of this joint would be suture in the skull. In children, the skull joint is not closed to permit the head to grow but in the adult, it is closed.
Amphiarthrosis joint permits a small movement. This included the intervertebral disc.
Diarthrosis permit a wide degree of movement. This joint is more complex because it has the synovial membrane. The complex structure makes the joints more durable to shock. This was vital because organ with this join used frequently. The example of this joints would be femur and pelvic(hip) joints. Joints in arm and leg mostly diarthrosis joint.
