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Lelechka [254]
3 years ago
9

What minimum number of 45 W lightbulbs must be connected in parallel to a single 240 V household circuit to trip a 50.0 A circui

t breaker? ____lightbulbs
Physics
1 answer:
Black_prince [1.1K]3 years ago
5 0

Answer:267

Explanation:

Given

Power of light bulbs is 45 W

and voltage applied is 240 V

Allowable current is 50 A

and P=\frac{V^2}{R}

R=\frac{V^2}{P}

R=\frac{240\times 240}{45}=1280 \Omega

and wire will trip if resistance drop below

R_{total}=\frac{240}{50}=4.8 \Omega

Therefore R_{total}=\frac{R}{n}

n=\frac{R}{R_{total}}=\frac{1280}{4.8}=266.667 \approx 267

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Is it possible for a car to be accelerating to the west while it is driving to the east?
Ber [7]

Answer:

Yes

Explanation:

If the acceleration has an opposite direction to the velocity of the car, this means that it is opposed to is motion. Therefore, it is called deceleration, since the car's velocity will decrease until it stops and then will start it moving towards the west.

8 0
3 years ago
What is the difference between the number of electrons in an atom of selenium, Se, and the number of electrons in an atom of alu
Oxana [17]
Well, electrons can be converted into a atomic number so if SE atomic number is 34 that means it has 34 electrons. AI has a atomic number of 13 meaning it has 13 electrons.

So the difference is that SE has more electrons then AI.

Hope this helped. :D
4 0
3 years ago
Read 2 more answers
2. A student places an object with a mass of m on a disk at a position r from the center of the disk. The student starts rotatin
ycow [4]

Answer:

\frac{0.065}{r}

Explanation:

The maximum velocity of an object moving in a curve beyond which it will slide off the curve is given by the relationship in equation (1);

v=\sqrt{\mu gr}....................(1)

where \mu is the coefficient of friction between the object and the surface of the curve, g is acceleration due to gravity and r is the radius of the curve.

Given;

v = 0.8m/s

g = 9.81m/s^2

r = ?

\mu=?

In order to solve for \mu, we can simply make it the subject of formula from equation (1) as follows;

v^2=\mu gr\\hence\\\mu=\frac{v^2}{gr}.................(2)

since we were not given the value of r, we can just substitute other known values, then solve and leave the answer in terms of r.

Therefore;

\mu=\frac{0.8^2}{9.81r}

\mu=\frac{0.64}{9.81r}\\\\\mu=\frac{0.065}{r}

8 0
3 years ago
Two planets, Dean and Sam, orbit the Sun. They each have with circular orbits, but orbit at different distances from the Sun. De
lyudmila [28]

Answer:

The correct answer is Dean has a period greater than San

Explanation:

Kepler's third law is an application of Newton's second law where the force is the universal force of attraction for circular orbits, where it is obtained.

                T² = (4π² / G M)  r³

When applying this equation to our case, the planet with a greater orbit must have a greater period.

Consequently Dean must have a period greater than San which has the smallest orbit

The correct answer is Dean has a period greater than San

3 0
2 years ago
An object at 27°C has its temperature increased to 37°C.
Firlakuza [10]

Answer:

b. 14

Explanation:

T_{i} = Initial temperature = 27 °C = 27 + 273 = 300 K

T_{f} = Final temperature = 37 °C = 37 + 273 = 310 K

P_{i} = Initial Power radiated by the object

P_{f} = Final Power radiated by the object

We know that the power radiated is directly proportional to fourth power of the temperature. hence

\frac{P_{f}}{P_{i}} = \frac{T_{f}^{4} }{T_{i}^{4} }\\\frac{P_{f}}{P_{i}} = \frac{(310)^{4} }{(300)^{4} }\\\frac{P_{f}}{P_{i}} = 1.14\\P_{f} = (1.14) P_{i}

Percentage increase in power is given as

\frac{(P_{f} - P_{i})\times100}{P_{i}} \\\frac{((1.14) P_{i} - P_{i})\times100}{P_{i}} \\14

3 0
3 years ago
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