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2 years ago

How are humans able to perceive light waves? Sound waves?

1 answer:

7 0

Sound and light are similar in that both are forms of energy that travel in waves. They both have properties of wavelength, freqency and amplitude. ... Sound is a form of mechanical energy caused by vibrations of matter. Light is electromagnetic energy caused by interacting electric and magnetic fields.

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I NEED HELP PLEASE, THANKS! Light passes from air into water at an angle of 40.0° to the normal. What is the angle of refraction

Vlad [161]

Answer:

Angle of Refraction = 28.9 degrees

Explanation:

We'll use Snell's law for this. It's mathematical form is:

=> $n_1* sin(\alpha _1)=n_2 * sin(\alpha _2)$

Where $n_{1} = 1, n_{2} = 1.33, \alpha _{2} = 40^o$

=> $n_{1}$ and $n_{2}$ are the refractive indexes of the air and water respectively.

Solution:

=> 1 * sin (40) = 1.33 * sin( $\alpha _{2}$ )

=> sin $\alpha _{2}$ = $\frac{sin 40^0}{1.33}$

=> sin $\alpha _{2}$ = 0.4821

=> $\alpha _{2}$ = 28.9 degrees

8 0

2 years ago

If a machine has an efficiency of 50% and an input of 3 J, what is the output?

uranmaximum [27]

Answer:

150J

Explanation:

work output/work input=100%

so just make work output the subject

6 0

2 years ago

A dart hits a dartboard and stops in 0.060 s. The net force on the dart is 14 N during the collision.

Rainbow [258]

Answer:

The change of momentum of the dart is 0.84 Nw.s

Explanation:

Impulse and change of momentum

The change in momentum of an object is its mass times the change in its velocity:

$\Delta p=m\Delta v=m(v_2-v_1)$

The change in the momentum can also be found by considering the force acting on it. If a force F acts for a time Δt, the change of momentum is given by:

$\Delta p=F.\Delta t$

The dart hits a dashboard with a net force of 14 N during the collision and stops in 0.06 seconds. The change of momentum is:

$\Delta p=14*0.06=0.84$

The change of momentum of the dart is 0.84 Nw.s

5 0

2 years ago

The circuit you should use to find the open-circuit voltage is

fiasKO [112]

Answer:

Incomplete questions check attachment for circuit diagram.

Explanation:

We are going to use superposition

So, we will first open circuit the current source and find the voltage Voc.

So, check attachment for open circuit diagram.

From the diagram

We notice that R3 is in series with R4, so its equivalent is given below

Req(3-4) = R3 + R4

R(34) = 20+40 = 60 kΩ

Notice that R2 is parallel to the equivalent of R3 and R4, then, the equivalent of all this three resistor is

Req(2-3-4) = R2•R(34)/(R2+R(34))

R(234) = (100×60)/(100+60)

R(234) = 37.5 kΩ

We notice that R1 and R(234) are in series, then, we can apply voltage divider rule to find voltage in R(234)

Therefore

V(234) = R(234) / [R1 + R(234)] × V

V(234) = 37.5/(25+37.5) × 100

V(234) = 37.5/62.5 × 100

V(234) = 60V.

Note, this is the voltage in resistor R2, R3 and R4.

Note that, R2 is parallel to R3 and R4. Parallel resistor have the same voltage, then voltage across R2 equals voltage across R34

V(34) = 60V.

Now, we also know that R3 and R4 are in series,

So we can know the voltage across R4 which is the Voc we are looking for.

Using voltage divider

V4 = Voc = R4/(R4 + R(34)) × V(34)

Voc = 40/(40+60) × 60

Voc = 24V

This is the open circuit Voltage

Now, finding the short circuit voltage when we short circuit the voltage source

Check attachment for circuit diagram.

From the circuit we notice that R1 and R2 are in parallel, so it's equivalent becomes

Req(1-2) = R1•R2/(R1+R2)

R(12) = 25×100/(25+100)

R(12) = 20 kΩ

We also notice that the equivalent of Resistor R1 and R2 is in series to R3. Then, the equivalent resistance of the three resistor is

Req(1-2-3) = R(12) + R(3)

R(123) = 20 + 20

R(123) = 40 kΩ

We notice that, the equivalent resistance of the resistor R1, R2, and R3 is in series to resistor R4.

So using current divider rule to find the current in resistor R4.

I(4) = R(123) / [R4+R(123)] × I

I(4) = 40/(40+40) × 8

I(4) = 4mA

Then, using ohms law, we can find the voltage across the resistor 4 and the voltage is the required Voc

V = IR

V4 = Voc = I4 × R4

Voc = 4×10^-3 × 40×10^3

Voc = 160V

Then, the sum of the short circuit voltage and the open circuit voltage will give the required Voc

Voc = Voc(open circuit) + Voc(short circuit)

Voc = 24 + 160

Voc = 184V.

3 0

2 years ago

How many normal modes of oscillation or natural frequencies does each if the following have: (

Vadim26 [7]

Each of these systems has exactly one degree of freedom and hence only one natural frequency obtained by solving the differential equation describing the respective motions. For the case of the simple pendulum of length L the governing differential equation is d^2x/dt^2 = - gx/L with the natural frequency f = 1/(2π) √(g/L). For the mass-spring system the governing differential equation is m d^2x/dt^2 = - kx (k is the spring constant) with the natural frequency ω = √(k/m). Note that the normal modes are also called resonant modes; the Wikipedia article below solves the problem for a system of two masses and two springs to obtain two normal modes of oscillation.

6 0

3 years ago