Sample Response: The properties of plastics make them useful in making products that are beneficial to society. Plastics and their production are costly, and are harmful to the environment, to humans, and to many other organisms.
There are both advantages and disadvantages in using plastics: The advantages are: Plastic is cheap to manufacture because it is easy to mold. It is light but durable and unbreakable. Plastic does not rust and it is water resistant. Plastic is reusable over and over again and when it is worn, the cost of replacement is cheaper than glass or rubber. It is odorless and chemical resistant. The disadvantages of plastic are: Plastic can cause cancer. Recycling plastic can cause toxic chemicals to be released during the process. It has low heat resistance and melts when placed near fires. Plastic containers for food absorb the smell of the food even when washed thoroughly. Small parts in plastic toys can cause choking in small children, the same with plastic bags when accidentally wrapped around children's heads. Plastics can clog up sewer systems when people through them away indiscriminately.
Assuming no friction on the rope or air resistance, we can apply the conservation of mechanical energy principle to the first part of the trajectory, from when Jane starts her swing till she catches Tarzan at the ground level.
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Rearranging terms, we get:
Now, as Jane starts from rest, Kij =0.
if we choose the ground level as our zero reference level, it will be also Ufj = 0.
Replacing in (2) by the expressions of Uij and Kfj, we have:
Replacing in (3) by the givens, and rearranging terms, we can solve for vfj, as follows:
Now, as once jane catches Tarzan, both continue swinging together, we can take the catching moment as a completely inelastic collision.
Assuming no external forces act during the collision, total momentum must be conserved.
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Assuming that Tarzan is at rest when Jane catches him, the initial momentum will be simply as follows:
The final momentum, will be just the product of the combined mass of Jane and Tarzan times the common speed for them after the collision:
As (6) and (7) are equal each other, we can solve for vjt, as follows:
Finally we can apply the same energy conservation principle to the last part of the trajectory, as follows:
We know that Uijt = 0 and also that Kfjt = 0, due to both starts from the ground level and reach to the highest point before starting to fall down, so at this point, the kinetic energy will be zero.
Replacing by the givens and the result from (8), we can solve for the h as follows:
A soundwave will go through a medium but once it goes through, the sound that you hear is muffled or not as clear usually just like sound going through a wall. The soundwaves will be something like moved and the sound you hear might not be the same or as clear as the original sound was