If a machine exerts a force of 250N on an object and no work is done, what must have occurred?
1 answer:
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1) See attached figure
The relationship between charge and current is:
where
i is the current
Q is the charge
t is the time
Therefore, the current is the rate of change of the charge passing through a given point over time.
This means that for a graph of charge over time, the current is just equal to the slope of the graph.
For the graph in this problem:
- Between t = 0 and t = 2 s, the slope is
therefore the current is
i = 25 A
- Between t = 2 s and t = 6 s, the slope is
therefore the current is
i = -25 A
- Between t = 6 s and t = 8 s, the slope is
therefore the current is
i = 25 A
The figure attached show these values plotted on a graph.
2)
The previous equation can be rewritten as
This equation is valid if the current is constant: if the current is not constant, then the total charge is simply equal to the area under a current vs time graph.
Here we have the current vs time graph, so we gave to find the area under it.
The area of the first triangle is:
While the area of the second square is
So, the total area (and the total charge) is
To solve this problem it is necessary to apply the concepts related to transformers, that is to say passive electrical device that transfers electrical energy from one electrical circuit to one or more circuits.
From the mathematical definition we have that the relationship between the voltage of the first coil and the second coil is proportional to the number of loops of the first and second loop, that is:
Where
input voltage on the primary coil.
input voltage on the secondary coil.
number of turns of wire on the primary coil.
number of turns of wire on the secondary coil.
Replacing our values we have:
Replacing,
From the same relations of number of turns and the voltage of the first and second coil we also have the relation of electricity and voltage whereby:
Where
= Current Primary Coil
= Current secundary Coil
Therefore:
Therefore the maximum values for the secondary coil of the voltage is 410.56V and Current is 1.87A