The highest energy waves in the electromagnetic spectrum are
1 answer:
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Answer:
19.95 J
Explanation:
The center of mass of the ladder is initially at a height of:
The center of mass of the ladder ends at a height of:
=L/2
So, the work done is equal to the change in potential energy which is:
W = PE =
now
therefore
W = [mgL/2]×[1 - sin(theta)]
W = [(7.30)(9.81)(2.50)/2]×[1-sin(51°)]
solving this we get
W = 19.95 J
Answer:
It will require a force of 1/5, answer A.
Explanation:
In the attached image we can see an example of an array of pulleys that will lift a 100 kg-f load.
If we analyze pulleys A,B, and C as in the image we can check a force in the cable of 20kg-f.
In the pulley D we have three forces of 20 kg-f each and those forces plus the forces in the pulley B, sum a total of 100 kg-f (60+40). This matches the mechanical advantage (100/5) = 20 kg-f
