Which is a source of AC current? A) a battery B) a generator C) chemical cells wired in series D) chemical cells wired in parall
2 answers:
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Answer:
a) Gravitational potential energy = 399 J
b) Gravitational potential energy = 66.5 J
c) Gravitational potential energy = 0 J
Explanation:
Hi there!
Please, see the attached figure for a better understanding of the problem.
a) When the ropes are horizontal, the height of the child, relative to the child's lowest position, is 2.10 m (see figure).
The gravitational potential energy is calculated as follows:
PE = mgh
Where:
PE = potential energy.
mg = weight of the child
h = height.
Then when the ropes are horizontal, the potential energy will be:
PE = 190 N · 2.10 m = 399 J
b) When the ropes make a 34.0° with the vertical, the height of the child is 2.10 m minus x (see figure). To find x, we can use trigonometry of right triangles:
cos angle = adjacent side / hypotenuse
cos 34.0° = x / 2.10 m
x = 2.10 m · cos 34.0° = 1.75 m
Then, the height of the child relative to the lowest position is
(2.10 m - 1.75 m) = 0.35 m
Therefore, the gravitational potential energy will be:
PE = 190 N · 0.35 m
PE = 66.5 J
c) When the child is at the bottom of the circular arc the height is zero (the child is at the lowest position), then, the gravitational potential energy will be zero.
During the fall, all the initial potential energy of the rock
has converted into kinetic energy of motion
where h is the initial height of the rock, m its mass, and v its velocity just before hitting the water. So, for energy conservation, we have
and so we can find the value of K, the kinetic energy of the rock just before hitting the ground:
has converted into kinetic energy of motion
where h is the initial height of the rock, m its mass, and v its velocity just before hitting the water. So, for energy conservation, we have
and so we can find the value of K, the kinetic energy of the rock just before hitting the ground: