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4 years ago

PLEASE HELP. HOW DO U CALCULATE??

Physics

1 answer:

tatyana61 [14]4 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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Elenna [48]

Stan looga
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3 years ago

Two balls have masses 18 kg and 47 kg. The 18 kg ball has an initial velocity of 76 m/s (to the right) along a line joining the

BigorU [14]

Answer:

The final velocity of 18 kg ball is $V_{2}$ = 42.09 $\frac{m}{sec}$

Explanation:

Mass of first ball $m_{1}$ = 18 kg

Mass of second ball $m_{2}$ = 47 kg

Initial velocity of 18 kg ball $V_{1}$ = 76 $\frac{m}{sec}$

Initial velocity of 47 kg ball = 0

Final velocity of 18 kg ball $V_{2}$ = ??

Final velocity of 18 kg ball is given by the formula

$V_{2}$ = $\frac{2 m_{1} V_{1} }{m_{1} + m_{2} }$

Put all the values in above formula we get

$V_{2}$ = 2 × 18 × $\frac{76}{65}$

$V_{2}$ = 42.09 $\frac{m}{sec}$

Thus, the final velocity of 18 kg ball is $V_{2}$ = 42.09 $\frac{m}{sec}$

3 0

3 years ago

Technician A says the parking brake cable adjustment should be performed before adjusting the rear brakes. Technician B says the

Firlakuza [10]

Answer:

Neither both are correct

Explanation:

The question involves the removal and installation procedure of cable for parking break. The answer for this could be found through the manual procedure for repairing parking break

Technician A is wrong because rear brakes should be adjusted before the parking cable adjustment is being made.

Technician B is wrong because the parking brake lever should be intact and secure at all clicks to allow maximum security. 15 clicks in this case should be the maximum number of clicks for the lever.

7 0

3 years ago

A billiard ball is moving in the x-direction at 30.0 cm/s and strikes another billiard ball moving in the y-direction at 40.0 cm

PSYCHO15rus [73]

Explanation:

Given that,

Initial speed of the billiard ball 1, u = 30i cm/s

Initial speed of another billiard ball 2, u' = 40j cm/s

After the collision,

Final speed of first ball, v = 50 cm/s

Final speed of second ball, v' = 0 (as it stops)

Let us consider that both balls have same mass i.e. m

Initial kinetic energy of the system is :

$K_i=\dfrac{1}{2}mu^2+\dfrac{1}{2}mu'^2\\\\K_i=\dfrac{1}{2}m(u^2+u'^2)\\\\K_i=\dfrac{1}{2}m((30)^2+(40)^2)\\\\K_i=1250m\ J$

Final kinetic energy of the system is :

$K_f=\dfrac{1}{2}mv^2+\dfrac{1}{2}mv'^2\\\\K_f=\dfrac{1}{2}m(v^2+v'^2)\\\\K_f=\dfrac{1}{2}m((50)^2+(0)^2)\\\\K_f=1250m\ J$

The change in kinetic energy of the system is equal to the difference of final and initial kinetic energy as :

$\Delta K=K_f-K_i\\\\\Delta K=1250m-1250m\\\\\Delta K=0$

So, the change in kinetic energy of the system as a result of the collision is equal to 0.

7 0

4 years ago

Why is a force required to keep a body moving with a uniform speed in a circular motion?

andrew-mc [135]

Because if there's no force on the object, then it just moves in a straight line.

6 0

4 years ago