Tim can type 2000 words at a speed of 50 words per minute bobs typing speed is 80 words per minute how much less time did bob ta
1 answer:
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Answer:
<em>a. 0.33 Amp</em>
<em>b. 2.4 Volt</em>
<em>c. 0</em>
<em>d. 2.45 Amp</em>
<em>e. Infinite</em>
<em>f. Series is safer</em>
Explanation:
<u>Series Connection of Resistors</u>
When two or more resistors are connected in series, the current through each one of them is the same, and the voltage divides depending on the particular value of each resistance. If all the resistances are equal, then the voltage is equally divided.
a. The string of 50 bulbs is connected to a 120 VAC outlet and consumes 40 W. The power of a circuit is given by
Solving for I
Since all the bulbs are connected in series the current is the same for all of them.
b. The voltage is equally divided, so each bulb has 120/50= 2.4 V
c. If one of the bulbs burns out and its resistance becomes infinite, then the series circuit is open and no current flows through it, neither through the rest of the bulbs. The typical case of the whole string going out.
d. If one of the bulbs short circuits, the resistance of that bulb is zero and the voltage is distributed by the 49 remaining bulbs. Thus the new current is
e. If the bulbs were connected in parallel, all of them would have the same voltage, and the total current will be equally divided among them. In that case, a short circuit in one of the bulbs will cause a parallel short, theoretically producing an infinite current and making the short circuit protection blow up.
f. The condition described above makes the strings be made of series-connected bulbs which is safer than the parallel circuit. If a single bulb shorts, the entire string goes out in a series connection, but the breaker would trigger disconnection of the house circuit if it's a parallel connection. That is why we must deal with unusable strings instead of burning cables.
Answer:
a)
b) mg>N
c)
d)
Explanation:
In order to solve part a) of the problem, we can start by drawing a free body diagram of the presented situation. (see attached picture).
In this case, we know the centripetal acceleration is given by the following formula:
where:
we know the period of rotation of the earth is about 24 hours, so:
so we can now find the angular speed:
So the centripetal acceleration will be:
which yields:
b)
In order to answer part b, we must draw a free body diagram of us sitting on a chair. (See attached picture.)
So we can do a sum of forces in equilibrium:
so we get that:
and solve for the normal force:
In this case, we can clearly see that:
therefore mg>N
This is because the centripetal acceleration is pulling us upwards, that will make the magnitude of the normal force smaller than the product of the mass times the acceleration of gravity.
c)
So let's calculate our weight and normal force:
Let's say we weight a total of 60kg, so:
and let's calculate the normal force:
N=586.58N
so now we can calculate the percentage change:
so we get:
which is a really small change.
d) In order to find this acceleration, we need to start by calculating the radius of rotation at that point of earth. (See attached picture).
There, we can see that the radius can be found by using the cos function:
In this case:
so we can solve for r, so we get:
in this case we'll use the average radius of earch which is 6,371 km, so we get:
which yields:
r=4,551.91 km
and now we can calculate the acceleration at that point:
