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3 years ago

What is the wavelength of a wave that has a speed of 3 km/s and a frequency of 12 Hz? A. 36 km B. 3.6 km C. 0.25 km D. 4 km

Physics

1 answer:

butalik [34]3 years ago

3 0

Answer:

c. 0.25km

Explanation:

v=f x wavelength

3000 = 12 x wavelength

wavelength = 3000/12 = 250m

250m to km

To convert m to km, we divide by 1000

250/1000 =0.25km

wavelength = 0.25km

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Find the ratio of the final speed of the electron to the final speed of the hydrogen ion, assuming non-relativistic speeds. Take

KiRa [710]

Answer:

$\frac{V_{e}}{V_{h}}=0.428*10^{2}$

Explanation:

From conservation of energy states that

$K_{i}+v_{i}=v_{f}+K_{f}\\ as\\K_{i}=0\\K_{f}=1/2mv^{2}\\ v_{i}=qv\\v_{f}=0\\So\\qv=1/2mv^{2}\\ v=\sqrt{\frac{2qv}{m} }\\ Velocity_{electron}=\sqrt{\frac{2qv}{m_{e}} }\\Velocity_{hydrogen}=\sqrt{\frac{2qv}{m_{h}} }\\\frac{V_{e}}{V_{h}}=\sqrt{\frac{\frac{2qv}{m_{e}}}{\frac{2qv}{m_{h}}}}\\\frac{V_{e}}{V_{h}}=\sqrt{\frac{m_{h}}{m_{e}} }\\\frac{V_{e}}{V_{h}}=\sqrt{\frac{1.67*10^{-27} }{9.11*10^{-31} } }\\\frac{V_{e}}{V_{h}}=0.428*10^{2}$

5 0

3 years ago

Which of the statements concerning light are true? The speed of light is the same no matter what material it is traveling throug

wel

Answer:

The statements that are true concerning light are the last three statements:

Its propagation direction is perpendicular to both the electric field and the magnetic field.

It moves at a constant speed through a vacuum.

The speed of light in matter is less than the speed of light in a vacuum.

Explanation:

Light is electromagnetic waves.

The properties of the electromagnetic waves were established by James Clerk Maxwell.

They included that they are the result of the oscillation of a magnetic field in phase with an electric field which are always is always perpendicular to each other.

Also, the electromagnetic waves propagate at right-angles to the direction of both the magnetic and the electric field, meaning that they are a type of transverse wave.

Thus, the second statement ("Its propagation direction is parallel to both the electric field and the magnetic field") is false, and the fourth statement ("Its propagation direction is perpendicular to both the electric field and the magnetic field") is true.

On the other hand, it is a postulate of the special theory of relativity that the speed of light is a constant (absolute value) in vacuum: nothing can travel faster than what light travels in vacuum. Thus, the fifth statement, "It moves at a constant speed through a vacuum" is true.

About the speed of light in matter, it is always less than the speed of light in vacuum. Thus, the first statement, "the speed of light is the same no matter what material it is traveling through", and the third statement "the speed of light in matter is greater than the speed of light in a vacuum" are false; while the last statement, "the speed of light in matter is less than the speed of light in a vacuum" is true.

The explanation on why the speed of light is less in a medium than in vacuum is related with the fact that at nanoscopic level the waves suffer polarization which means deviations from the straighi path, which makes that the net straight propagation is slower.

8 0

3 years ago

A 3.00-kg model airplane has velocity components of 5.00 m/s due east and 8.00 m/s due north. What is the plane’s kinetic energy

GalinKa [24]

Answer:

Kinetic energy, E = 133.38 Joules

Explanation:

It is given that,

Mass of the model airplane, m = 3 kg

Velocity component, v₁ = 5 m/s (due east)

Velocity component, v₂ = 8 m/s (due north)

Let v is the resultant of velocity. It is given by :

$v=\sqrt{v_1^2+v_2^2}$

$v=\sqrt{5^2+8^2}=9.43\ m/s$

Let E is the kinetic energy of the plane. It is given by :

$E=\dfrac{1}{2}mv^2$

$E=\dfrac{1}{2}\times 3\ kg\times (9.43\ m/s)^2$

E = 133.38 Joules

So, the kinetic energy of the plane is 133.38 Joules. Hence, this is the required solution.

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3 years ago

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James observes that the Polaris star in the northern hemisphere does not rise and set in the sky. His teacher tells him that thi

Nimfa-mama [501]

Answer:

Just above the pole (top-most red circle)

Explanation:

Polaris is used to identify North direction. Since, the Earth rotates on its axis which is along North-south, Polaris never seems to rise and set from the Northern hemisphere. This is because Polaris lies above north pole. Thus, in the given diagram, Polaris is above the North pole on the axis represented by top-most red circle.

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3 years ago

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A box slides down a ramp. Which statement is true about the kinetic and potential energy of the box?

lbvjy [14]

Its potential energy decreases and kinetic energy.

6 0

3 years ago

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