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vivado [14]
3 years ago
5

How much power is required to light a lightbulb at 100V of voltage when the lightbulb has a resistance of 500 Ohms?

Physics
1 answer:
salantis [7]3 years ago
3 0

Answer:

Power = 20 Watts

Explanation:

Given the following data;

Voltage = 100 V

Resistance = 500 Ohms

To find the power that is required to light a lightbulb;

Mathematically, power can be calculated using the formula;

Power = \frac {Voltage^{2}}{resistance}

Substituting into the formula, we have;

Power = \frac {100^{2}}{500}

Power = \frac {10000}{500}

Power = 20 Watts

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If P = 4.00î + 3.00k, P · Q = 17.0, and P ✕ Q = −6.00ĵ, determine the vector Q.
Butoxors [25]

let the vector Q is given as

\vec Q = a\hat i + b\hat j + c\hat k

given that

P X Q = -6\hat j

here we know that

P = 4\hat i + 3 \hatk

now by above equation

(4\hat i + 3\hat k) X (a\hat i + b\hat j + c\hat k) = - 6\hat j

4b\hat k - 4c\hat j + 3a\hat j - 3b\hat i = - 6\hat j

so by comparing both sides

b = 0

4c - 3a = 6

also we know that

a^2 + b^2 + c^2 = 17^2

a^2 + 0 + (1.5 + 0.75a)^2 = 289

by solving above equation

a = 12.85 and c = 11.14

so the vector Q is given as

Q = 12.85\hat i + 11.14\hat k

8 0
3 years ago
It has been argued that power plants should make use of off-peak hours (such as late at night) to generate mechanical energy and
Trava [24]

Answer:

Explanation:

kinetic energy = 14.1 MJ = 14.1 x 10⁶ J

Let radius of flywheel be r .

volume of flywheel = π r² x t where t is thickness

= 3.14 x r² x .113 m³

= .04 r² m³

mass = volume x density

= .04 r² x 7800 = 312.73 r²kg

moment of inertia I = 1 / 2 mass x radius²

= .5 x 312.73 r² x r²

= 156.37 r⁴ kg m²

angular velocity ω = 2π x 93/60

= 9.734 rad /s

kinetic energy = 1/2 Iω² where ω is angular velocity

= .5 x 156.37 r⁴ x 9.734²

= 7408.08 r⁴

Given

7408.08 r⁴ =  14.1 x 10⁶

r⁴ = .19 x 10⁴

r = .66 x 10

= 6.60 m .

Diameter = 13.2 m

b )

centripetal acceleration of a point on its rim = ω² r

= 9.734² x 6.6

= 625.35 m /s²

5 0
3 years ago
What is the frequency of microwaves of wavelength 3 cm?
tiny-mole [99]

Answer:

10 GHz

Explanation:

Applying,

v = λf.................... Equation 1

Where v = speed of microwave, λ = wavelength, f = frequency.

make f the subject of the equation

f = v/λ................ Equation 2

Note: Microwave is an electromagnetic wave, and all electromagnetic wave have the same speed, which is 3×10⁸ m/s

From the question,

Given: λ = 3 cm = 0.03 m

Constant; v = 3×10⁸ m/s

Substitute these values into equation 2

f = 3×10⁸/(0.03)

f = 10¹⁰ Hz

f = (10¹⁰/10⁹) GHz

f = 10 GHz

4 0
2 years ago
Violet light of wavelength 405 nm ejects electrons with a maximum kinetic energy of 0.890 eV from a certain metal. What is the b
AleksandrR [38]

Answer:

  Ф = 2.179 eV

Explanation:

This exercise has electrons ejected from a metal, which is why it is an exercise on the photoelectric effect, which is explained assuming the existence of energy quanta called photons that behave like particles.

            E = K + Ф

the energy of the photons is given by the Planck relation

            E = h f

we substitute

           h f = K + Ф

           Ф= hf - K

the speed of light is related to wavelength and frequency

            c = λ f

            f = c /λ

            Φ = \frac{hc}{\lambda } - K

let's reduce the energy to the SI system

            K = 0.890 eV (1.6 10⁻¹⁹ J / 1eV) = 1.424 10⁻¹⁹ J

calculate

           Ф = 6.63 10⁻³⁴ 3 10⁸/405 10⁻⁹  -1.424 10⁻¹⁹

           Ф = 4.911 10⁻¹⁹ - 1.424 10⁻¹⁹

           Ф = 3.4571 10⁻¹⁹ J

         

we reduce to eV

           Ф = 3.4871 10⁻¹⁹ J (1 eV / 1.6 10⁻¹⁹ J)

           Ф = 2.179 eV

4 0
2 years ago
On a highway, a car is driven 80. kilometers
nydimaria [60]

The average speed of the car for the entire trip can be calculate by using:

v=\frac{S}{t}

where S is the total distance covered by the car, and t is the total time taken.


The total distance travelled by the car is:

S=80 km+50 km+40 km=170 km

while the total time taken is:

t=1.00 h+0.50 h+0.50 h=2.00 h


so, the average speed of the car is:

v=\frac{S}{t}=\frac{170 km}{2.00 h}=85 km/h


so, the correct answer is (3) 85 km/h.

7 0
3 years ago
Read 2 more answers
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