A light-emitting diode (LED) connected to a 3.0 V power supply emits 440 nm blue light. The current in the LED is 11 mA , and the LED is 51 % efficient at converting electric power input into light power output. How many photons per second does the LED emit?

Answer:

C

Explanation:

When a ball rolls down a hill, Potential Energy Conversion takes place to Kinetic Energy.

Answer:

100 V

Explanation:

V = I * R

V = 2 * 50

V = 100 V

{ I think there is a mistake in the options. }

Answer:

The speed of the ball when it reaches equilibrium position is 3.31 m/s

Explanation:

Given;

mass of the object, m = 0.25 kg

initial displacement of the object, h₁ = 0.56 m

spring constant, k = 105 N/m

displacement at equilibrium position, h₂ = 0

initial velocity of the object, v₁ = 0

velocity of the object at equilibrium position = v₂

The change in gravitational potential energy at the equilibrium position is given as;

ΔP.E = mg(h₂ - h₁)

The change in kinetic energy of the object at the equilibrium position is given as;

ΔK.E = ¹/₂m(v₂² - v₁²)  

Apply the principle of conservation of mechanical energy;

ΔK.E  +  ΔP.E = 0

¹/₂m(v₂² - v₁²)  +  mg(h₂ - h₁) = 0

¹/₂m(v₂² - 0)  +  mg(0 - h₁) = 0

¹/₂mv₂²  -  mgh₁  =  0

¹/₂mv₂²  = mgh

¹/₂v₂² = gh

v₂² = 2gh

v₂ = √2gh

v₂ = √(2 x 9.8 x 0.56)

v₂ = 3.31 m/s

Therefore, the speed of the ball when it reaches equilibrium position is 3.31 m/s

(a) When the spring is compressed 4.5 cm = 0.045 m, it exerts a restoring force on the block of magnitude

F = (1900 N/m) (0.045 m) = 85.5 N

so that at the moment the block is released, this force accelerates the block with magnitude a such that

85.5 N = (1.15 kg) a   ==>   a = (85.5 N) / (1.15 kg) ≈ 74.3 m/s²

The block reaches its maximum speed at the spring's equilbrium point, and this speed v is such that

v ² = 2 (74.3 m/s²) (0.045 m)   ==>   v = √(2 (74.3 m/s²) (0.045 m)) ≈ 2.59 m/s

(b) There is no friction between the block and plane, so the block maintains this speed as it slides over the edge. At that point, it's essentially in free fall, so if y is the height of the plane, then

(7 m/s)² - (2.59 m/s)² = 2gy   ==>   y = ((7 m/s)² - (2.59 m/s)²) / (2g) ≈ 2.16 m

Answer:

0.3817 N

Explanation:

Remark

One thing is certain: the ball has a mass of 101 grams wherever it is in the universe. That is not true of the force. The force on the moon is a whole lot less than it is on earth, and maybe planet x as well.

Givens

m = 101 g

vi = 0       That's what at rest means.

t = 2.91 s

d = 16 m

F= ?

Formulas

d = vi*t + 1/2*a * t^2

Force = m * a

Solution

16 = 0 + 1/2 a * 2.91^2

16 = 4.234 a                       Divide by 4.234

16/4.234 = a

a = 3.779

F = m * a

a = 3.779

m = 101 g = 1 kg / 1000 grams

m = 0.101 kg

F = 0.101 * 3.779

F = 0.3817N

Answer:

Answer:

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Answer: Geothermal energy is produced by the heat of Earth's molten interior. This energy is harnessed to generate electricity when water is injected deep underground and returns as steam (or hot water, which is later converted to steam) to drive a turbine on an electric power generator.

Explanation: Hope this helps!

Answer:

Final velocity = 10 m/s

Time taken to travel 100 meter = 8.16 second (Approx.)

Explanation:

Given:

Acceleration = 2 m/s²

Initial velocity = 0 m/s

Find:

Velocity after 5 seconds

Time taken to travel 100 meter

Computation:

Using first equation of motion

v = u + at

v = 0 + (2)(5)

Final velocity = 10 m/s

Using Second equation of motion

s = ut + (1/2)(a)(t²)

100 = (0)(t) + (1/2)(3)(t²)

100 = (1/2)(2)(t²)

100  = (t²)

t = 10

Time taken to travel 100 meter = 8.16 second (Approx.)

Answer:

C

Explanation:

I think it would be there, it sounds like silicone and thats on the right side

Answer:

[tex]a_2=3.88m/s^2[/tex]

Explanation:

From the Question we are told that:

Initial Mass [tex]m_1=1300kg[/tex]

Final mass [tex]m_2=1300+400=>1700kg[/tex]

[tex]a_1=3.0m/s^2[/tex]

Generally the equation for  Force  is mathematically given by

 [tex]F=m_1a_1[/tex]

 [tex]F=1300*5[/tex]

 [tex]F=6500N[/tex]

Generally the equation for Final acceleration  is mathematically given by

 [tex]F'=m_2*a_2[/tex]

 [tex]a_2=\frac{6500}{1700}[/tex]

 [tex]a_2=3.88m/s^2[/tex]

Answer:

the answer is B i hope it helps :)

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B. The energy required to force two nuclei to undergo nuclear fusion. ✅

[tex]\large\mathfrak{{\pmb{\underline{\orange{Happy\:learning }}{\orange{!}}}}}[/tex]

Answer:

31475404.8 kg/day

Explanation:

From the information given:

The power plant capacity W = 3570 MW

Energy content of the coal = 28000 kJ/kg

let assume that the thermal efficiency = 35%

Recall that:

1 kw = 3600 kJ/hr provided that the energy conversion is 100% efficient

But assuming the thermal efficiency = 35%.

Then:

Heat input = 3600/0.35 = 10286 kJ/kw.hr

Now, for producing 1 kw.hr, the quantity of the required coal = 10286/28000

= 0.36736 kg

For 3570 MW, the amount of coal that must be input is:

= 0.36736 kg × 3570000

= 1311475.2 kg/hr

= 1311475.2 × 24 kg/day

= 31475404.8 kg/day

d. An object did work on the environment.

Work is defined in many contexts. Some of these are;

i. Work is the product of force and displacement. In this case, work done is positive if the force applied on an object or body and the displacement caused by the force are in the same direction. If instead the force and displacement are in opposite direction, then the work done will be negative. If it is the case the force and the displacement are perpendicular to each other, the work done is zero.

ii. In the first law of thermodynamics, the internal energy of a system is the sum of the work done and the heat exchanged between the system and the environment. Therefore, work done is the difference between the internal energy of a system and the heat exchanged between the system and the environment.

In this case, work is said to be positive if work is done by the system (object) on the environment. It is negative if work is done by the environment on the system (object).

Answer:

its c

Explanation:

Answer:

physical science is important

hety

civil engineering

Answer:

Explanation:

Given that:

Focal length for the objective lens = 20 mm, 4 mm, 1.4 mm

For objective lens of focal length f₁ = 20 mm

s₁' = 120 mm + 20 mm = 140 mm

∴

Magnification [tex]m_1 = \dfrac{s'_1}{f_1}[/tex]

[tex]m_1 = \dfrac{140}{20}[/tex]

[tex]m_1 = 7 \ m[/tex]

For objective lens of focal length f₁ = 4 mm

s₁' = 120 mm + 4 mm = 124 mm

[tex]m_1 = \dfrac{s'_1}{f_1}[/tex]

[tex]m_1 = \dfrac{124}{4}[/tex]

[tex]m_1 = 31 \ m[/tex]

For objective lens of focal length f₁ = 1.4 mm

s₁' = 120 mm + 1.4 mm = 121.4 mm

[tex]m_1 = \dfrac{s'_1}{f_1}[/tex]

[tex]m_1 = \dfrac{121.4}{1.4}[/tex]

[tex]m_1 = 86.71 \ m[/tex]

The magnification of the eyepiece is given as:

[tex]m_e = 5X \ and \ m_e = 15X[/tex]

Thus, the largest angular magnification when  [tex]m_1 \ and \ m_e \ are \ large \ is:[/tex]

[tex]M_{large}= (m_1)_{large} \times (m_e)_{large}[/tex]

= 86.71 × 15

= 1300.65

The smallest angular magnification derived when [tex]m_1 \ and \ m_e \ are \ small \ is:[/tex]

[tex]M_{small}= (m_1)_{small} \times (m_e)_{small}[/tex]

= 7 × 5

= 35

The largest magnification will be 1300.65 and the smallest magnification will be 35.

Magnification is defined as the ratio of the size of the image of an object to the actual size of the object.

Now for objective lens and eyepieces, it is defined as the ratio of the focal length of the objective lens to the focal length of the eyepiece.

It is given in the question:

Focal lengths for the objective lens is = 20 mm, 4 mm, 1.4 mm

now we will calculate the magnification for all three focal lengths of the objective lens.

Also, each objective forms an image 120 mm beyond its second focal point.

(1) For an objective lens of focal length   [tex]f_1=20 \ mm[/tex]

[tex]s_1'=120\ mm +20 \ mm =140\ mm[/tex]

Magnification will be calculated as

[tex]m_1=\dfrac{s_1'}{f_1} =\dfrac{140}{20} =7[/tex]

(2) For an objective lens of focal length [tex]f_1= \ 4 \ mm[/tex]

s₁' = 120 mm + 4 mm = 124 mm

[tex]m_1=\dfrac{s_1'}{f_1} =\dfrac{124}{4} =31[/tex]

(3) For an objective lens of focal length [tex]f_1=1.4\ mm[/tex]

s₁' = 120 mm + 1.4 mm = 121.4 mm

[tex]m_1=\dfrac{s_1'}{f_1} =\dfrac{121.4}{1.4} =86.71[/tex]

Now the magnification of the eyepiece is given as:

[tex]m_e=5x\ \ \ & \ \ m_e=15x[/tex]

Thus, the largest angular magnification when  

[tex]m_1 = 86.17\ \ \ \ m_e=15x[/tex]

[tex]m_{large}= (m_1)_{large}\times (m_e)_{large}[/tex]

[tex]m_{large}=86.71\times 15=1300.65[/tex]

The smallest angular magnification derived when

[tex]m_1=7\ \ \ \ m_e=5[/tex]

[tex]m_{small}=(m_1)_{small}\times (m_e)_{small}[/tex]

[tex]m_{small}=7\times 5=35[/tex]

Thus the largest magnification will be 1300.65 and the smallest magnification will be 35.

To know more about magnification follow

https://brainly.com/question/1599771

Answer:

option C is the correct one

Explanation:

I hope it helps u

Answer:

Moving electrons always create a magnetic field. Electrons moving along a wire make a magnetic field that goes in circles around the wire. When you bend the wire into a coil, the magnetic fields around each loop of the coil add up to make a long , thin magnet with north at one end and south at the other.

Explanation:

Answer:

The impulse delivered to the ball is [tex]Imp = \left(-3.941, 1.975\right)\,\left[\frac{kg\cdot m}{s} \right][/tex].

Explanation:

By Impulse Theorem, the motion of the tennis ball is modelled after the following expression:

[tex]Imp = m\cdot (\vec v_{f} - \vec v_{o})[/tex] (1)

Where:

[tex]m[/tex] - Mass of the ball, in kilograms.

[tex]\vec v_{o}[/tex] - Vector of the initial velocity, in meters per second.

[tex]\vec v_{f}[/tex] - Vector of the final velocity, in meters per second.

[tex]Imp[/tex] - Impulse, in meters per second.

If we know that [tex]m = 0.06\,kg[/tex], [tex]\vec v_{o} = \left(45\,\frac{m}{s} \right)\cdot (\cos 47^{\circ}, \sin 47^{\circ})[/tex] and [tex]\vec v_{f} = \left(35\,\frac{m}{s} \right)\cdot (-1, 0)[/tex], then the impulse delivered to the ball is:

[tex]Imp = (0.06\,kg)\cdot \left[\left(35\,\frac{m}{s} \right)\cdot (-1,0) -\left(45\,\frac{m}{s} \right)\cdot (\cos 47^{\circ}, \sin 47^{\circ})\right][/tex]

[tex]Imp = (0.06\,kg)\cdot (-65.670, -32.911)\,\left[\frac{m}{s} \right][/tex]

[tex]Imp = \left(-3.941, 1.975\right)\,\left[\frac{kg\cdot m}{s} \right][/tex]

The impulse delivered to the ball is [tex]Imp = \left(-3.941, 1.975\right)\,\left[\frac{kg\cdot m}{s} \right][/tex].

Answer:

a)  [tex]V=7.5m/s[/tex]

b) [tex]rms=8.4m/s[/tex]

c) Generally the most probable speed is 8m/s as it the most posses by particles being the average

Explanation:

From the question we are told that:

Sample size N=15

  [tex]Speed 1 v_1=2m/s\\\\Speed 2 v_2=3m/s\\\\Speed 3 v_2=5m/s\\\\Speed 4 v_4=8m/s\\\\Speed 3 v_5=9m/s\\\\Speed 2 v_6=15m/s\\\\[/tex]

Generally the equation for Average speed is mathematically given by

 [tex]V_{avg}=\frac{\sum(nv)}{N}[/tex]

Therefore

 [tex]V_{avg}=\frac{(2+2(3)+3(5)+4(8)+3(9)+2(15))}{15}[/tex]

 [tex]V=7.5m/s[/tex]

b)

Generally the equation for RMS speed of the particle is mathematically given by

  [tex]rms=\sqrt{\frac{\sum(nv^2)}{N}}[/tex]

  [tex]rms=\sqrt{\frac{2^2+2(3)^2+3(5)^2+4(8)^2+3(9)^2+2(15)^2}{15}}[/tex]

  [tex]rms=\sqrt{69.73}[/tex]

  [tex]rms=8.4m/s[/tex]

c

Generally the most probable speed is 8m/s as it the most posses by particles being the average

Answer: 1 cal is 4.186 J, 1 kcal = 4186 J   A : 1014 m , B  200 m

Explanation:   A) Work done by climber is change in potential energy.

W = ΔEp = mgh = 67.0 kg· 9.81 m/s²· h = 160 kcal · 4186 J / kcal.

Solve h  =  160 kcal · 4186 J / kcal /67.0 kg· 9.81 m/s² = 1014 m

B  Energy is only 20 %  :   Then  h  =  0.20 ·160 kcal · 4186 J / kcal /67.0 kg· 9.81 m/s² = 200 m.

Actually, muscles also produce heat from most of the energy provided by food.

Answer:

To correct the defects of vision by measuring the radius of curvature and thus the power of the lenses.

Explanation:

A spherometer is an instrument used to measure the curvature of objects such as lenses and curved mirrors.

Generally it consists of a fine screw which is moving in a nut carried on the center of a 3 small legged table or frame. The feet forms the vertices of an equilateral triangle. The lower end of the screw and those of the table legs are finely tapered and terminate in hemispheres.

If the screw has two turns of the thread to the milli meter the head is generally divided into 50 equal parts, so that differences of 0.01 millimeter may be measured without using a vernier scale.

The spherometer is used to measure the radius of curvature of the lenses so that the opthalmologist find the focal length of the lens and then give the  power to the lens to correct the defects of vision.  

Answer:

The Sum of mass and energy is always conserved in a nuclear reaction. Mass changes to energy, but the total amount of mass and energy combined remains the same

Explanation:

Every single radioactive decay, every single nuclear collision, every single nuclear reaction will conserve mass number and charge.

Complete Question

A car is moving at 56 miles per hour. The kinetic energy of that car is 5 × 105 J. How much energy does the same car have when it moves at 90 miles per hour? Answer in units of J

Answer:

 [tex]K.E_2=640000J[/tex]

Explanation:

From the question we are told that:

Initial Velocity [tex]v_1=56 mil/h=>25.0342m/s[/tex]

 [tex]K.E_1=5*10^5J[/tex]

Final Velocity [tex]V_2=90mil/h=>40.2336m/s[/tex]

Generally the equation for  Kinetic Energy  is mathematically given by

 [tex]K.E=0.5mv^2[/tex]

Therefore

 [tex]K.E_1=0.5mv_1^2[/tex]  

 [tex]5*10^5J=m(25.0342)^2[/tex]

 [tex]m=797.82kg[/tex]

Therefore The Final K.E_2 is

 [tex]K.E_2=0.5mv_2^2[/tex]

 [tex]K.E_2=0.5*(797.82kg)(40.2336m/s)^2[/tex]

 [tex]K.E_2=640000J[/tex]

Answer:

inertia

Explanation:

Answer:

[tex]\lambda=1.39\times 10^{-4}\ s^{-1}[/tex]

Explanation:

Given that,

The half-life of Barium-139 is [tex]4.96\times 10^3[/tex]

A sample contains [tex]3.21\times 10^{17}[/tex] nuclei.

We need to find the decay constant for this decay. The formula for half life is given by :

[tex]T_{1/2}=\dfrac{0.693}{\lambda}\\\\\lambda=\dfrac{0.693}{T_{1/2}}[/tex]

Put all the values,

[tex]\lambda=\dfrac{0.693}{4.96\times 10^3}\\\\=1.39\times 10^{-4}\ s^{-1}[/tex]

So, the decay constant is [tex]1.39\times 10^{-4}\ s^{-1}[/tex].