Invented by Archimedes around 250 BC, a Block is a set of pulleys on an axle in a housing. When rope is run through a block or a series of blocks, the whole assembly is called a Tackle. The most common arrangement is to have one1 block attached to a fixed position and another block left to move with the load being pulled or lifted. The mechanical advantage of a block and tackle is equal to the number of time the same line is attached to or runs through the moving block. The pulley on the left does not have a block on the Bale. When you pull on the rope, you are pulling the full weight of the bail. The tackle on the right has 4 lines running through its pulleys. This would allow you to lift 20 pounds with only about 5 pounds of pressure on the hauling part of the line. While the block and tackle is still used today, it has been largely replaced with the electric winch.
The rope used in the 1800's would have been of natural fiber like we have in this exhibit. The rope around the bail is made of SISAL which comes from the leaves of the agave plant. Cotton rope is running in the blocks. Notice how soft it is compared to the SISAL fiber rope. Jute fiber twine, from the Corchorus plant, is used to tie the ends of the larger ropes. It is the same fiber woven to make burlap sacks. Natural fiber rope continued to be in widespread use until the 1950s when synthetic fibers, such as nylon, became popular.
Answer:
Resource people are experts or authorities who contribute information and opinions to participants in a learning situation. They frequently are used to conduct educational activities, but may also be helpful to your committee at the program planning stage. Resource people may be from within or outside the organization.
The exclusion of insects may be seen in freezing, burial, or wrapping. I<span>nsects and rodents are small and sneaky, many commercial buildings are rife with cracks, holes and other entry points that make ideal doorways for pests. I hope it helps. </span>
The correct answer is letter b. adrenaline secreted by the adrenal glands.
The heart pumps harder and blood pressure rises during a fight-or-flight response. This response is due to adrenaline secreted by the adrenal glands. Adrenaline is <span>a substance that is released in the body of a person who is feeling a strong emotion.</span>
Answer:
The person was born in 2005 B.C. (Before Christ). Therefore, he was 5 years old in 2000 B.C, 10 in 1995 B.C, and 15 in 1990 B.C.
Explanation:
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