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3 years ago

PLEASE HELP. HOW DO U CALCULATE??

Physics

1 answer:

tatyana61 [14]3 years ago

5 0

-- The energy of one photon is (h · frequency of the light)

' h ' is 6.626 × 10⁻³⁴ m²-kg/s ("Planck's Constant")

-- The question doesn't tell you the frequency of the light from the LED, but it tells you the wavelength, and

Frequency = (speed of light) / (wavelength) .

-- Now you have everything you need to calculate the energy carried by one photon from the LED.

-- The power of the light from the LED is 120 milliwatts. That's 0.120 Joule of energy per second.

Now you should be able to find the number of photons per second. It's going to be (0.120 Joule) / (energy carried by one photon) .

When I scribbled it out on a scrap of scratch paper, I got 3.853 x 10³⁸ photons, but you'd better really check that out.

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With what speed must you approach a source of sound to observe a 25% change in frequency?

insens350 [35]

Sound source is at rest, you are moving with velocity v, f = frequency, c = speed of sound:

f = f0(1 + v/c)

115 = 100(1 + v/343)
115 = 100 + 100v/343
15 = 100v/343
v = 15*343/100
 v = 51,45 m/s

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3 years ago

Because weight is a measurement of the amount of gravity pulling on an object, weight is considered a ______. Question 18 option

Andrews [41]

Answer: Force I believe.

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2 years ago

A pendulum oscillates 12 times in 4 seconds. what is the length of the pendulum?

seraphim [82]

Answer:

L = 2.8 cm

Explanation:

Period T = 4 / 12 = 1/3 s

T = 2π√(L/g)

L = (T/2π)²g

L = ((1/3)/2π)²9.8 = 0.02758... ≈ 2.8 cm

6 0

3 years ago

Calculate the acceleration of a bus that goes

Svet_ta [14]

The acceleration of the bus is 1.11 meters per second square to the direction of motion

Explanation:

Acceleration is the rate of change of velocity

The formula of the acceleration is $a=\frac{v_{2}-v_{1}}{t}$ , where

$v_{1}$ is the initial velocity

$v_{2}$ is the final velocity
t is the time

A bus that goes from 10 km/h to a speed of 50 km/h in 10 seconds

→ $v_{1}$ = 10 km/h

→ $v_{2}$ = 50 km/h

→ t = 10 seconds

Change the unite of the time from seconds to hour

→ 1 hour = 60 × 60 = 3600 seconds

→ 10 seconds = $\frac{10}{3600}=\frac{1}{360}$ hour

Substitute these values in the formula of the acceleration above

→ $a=\frac{50-10}{\frac{1}{360}}$

→ a = 14400 km/h²

To change the unit of acceleration to meter per second change the

kilometer to meter and the hour to seconds

→ 1 km = 1000 m

→ 1 hour = 3600 seconds

→ $a=\frac{14400*1000}{(3600)^{2}}=\frac{10}{9}$

→ a = 1.11 m/sec².

The acceleration of the bus is 1.11 meters per second square to the direction of motion

Learn more:

You can learn more about the acceleration in brainly.com/question/6323625

#LearnwithBrainly

4 0

3 years ago

Consider the speed of light in another universe to be only 100 m/s. Two cars are traveling along a highway in opposite direction

olganol [36]

Answer:

-62.45m/s and +62.45m/s

Explanation:

The formula for relativistic speed

This is the speed of A with respect to B

$V_{AB}=\frac{V_{A}-V_{B}}{1-\frac{V_{A}V_{B}}{C^2} }$

where

$V_{A}$ will be the velocity of person 1: 39m/s

$V_{B}$ will be the velocity of person 2: -31m/s (negative because is travelling in opposite direction)

and $C$ the velocity of light: 100m/s

The velocity of person 1 measured by person 2 is:

$V_{AB}=\frac{39m/s-(-31m/s)}{1-\frac{(39m/s)(-31m/s)}{(100m/s)^2}}=62.45m/s$

The velocity of person 2 measured by person 1 is:

$V_{BA}=\frac{V_{B}-V_{A}}{1-\frac{V_{B}V_{A}}{C^2} }$

$V_{BA}=\frac{-31m/s-39m/s}{1-\frac{(-31m/s)(39m/s)}{(100)^2} }=-62.45m/s$

8 0

3 years ago