Answer:
A. K = 0.546 eV
B. cooper and iron will not emit electrons
Explanation:
A. This is a problem about photoelectric effect. Then you have the following equation:
(1)
K: kinetic energy of the ejected electron
Ф: Work function of the metal = 2.48eV
h: Planck constant = 4.136*10^{-15} eV.s
λ: wavelength of light = 410nm - 750nm
c: speed of light = 3*10^8 m/s
As you can see in the equation (1), higher the wavelength, lower the kinetic energy. Then, the maximum kinetic energy is obtained with the lower wavelength (410nm). Thus, you replace the values of all variables :

B. First you calculate the energy of the photon with wavelengths of 410nm and 750nm

You compare the energies E1 and E2 with the work functions of the metals and you can conclude:
sodium = 2.3eV < E1
cesium = 2.1 eV < E1
cooper = 4.7eV > E1 (this metal will not emit electrons)
iron = 4.5eV > E1 (this metal will not emit electrons)
Answer:
it is 30 newtons to the left
Explanation:
We have that for the Question "Write an expression for the <em>magnitude </em>of charge moved, Q, in terms of N and the fundamental charge e" it can be said its equation is

From the question we are told
Write an expression for the <em>magnitude </em>of charge moved, Q, in terms of N and the fundamental charge e
<h3>An E
xpression for the <em>magnitude </em>of charge moved</h3>
Generally the equation for the <em>magnitude </em>of charge moved, Q is mathematically given as

Therefore
An expression for the <em>magnitude </em>of charge moved, Q, in terms of N and the fundamental charge e" it can be

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Answer:
She covers the distance is 12 km.
The magnitude of displacement is 8.6 km.
The direction of her displacement is north east.
Explanation:
Given that,
Christina drives his moped 7 kilometers North and stop for lunch and then drive 5 km east.
We need to calculate the total distance
Using formula of distance

Put the value into the formula


We need to calculate the magnitude of displacement
Using formula of displacement




The direction of her displacement is north east.
Hence, She covers the distance is 12 km.
The magnitude of displacement is 8.6 km.
The direction of her displacement is north east.
Answer:
<em>The centripetal acceleration would increase by a factor of 4</em>
<em>Correct choice: B.</em>
Explanation:
<u>Circular Motion</u>
The circular motion is described when an object rotates about a fixed point called center. The distance from the object to the center is the radius. There are other magnitudes in the circular motion like the angular speed, tangent speed, and centripetal acceleration. The formulas are:


If the speed is doubled and the radius is the same, then


The centripetal acceleration would increase by a factor of 4
Correct choice: B.