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3 years ago

how much work is done in holding a 15N sack of potatos while waiting in line at the grocery store for 3 minutes

1 answer:

7 0

The strict scientific definition of work is

Work = (force) x (distance) .

If you exert a force but not through any distance, then technically,
no work has been done. You may break out in sweat, and your arm
may start to tremble and ache. But according to Physics, no work
has been done until you lift that bale a little higher.

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A photoelectric effect experiment finds a stopping potential of 1.93 V when light of wavelength 200 nm is used to illuminate the

PSYCHO15rus [73]

a) zinc

The equation of the photoelectric effect is:

$E=\phi + K$ (1)

where

E is the energy of the incident light

$\phi$ is the work function

$K$ is the maximum kinetic energy of the emitted photoelectrons

Here the wavelength of the incident light is

$\lambda=200 nm = 2\cdot 10^{-7} m$

so the energy of the light is

$E=\frac{hc}{\lambda}=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{2\cdot 10^{-7} m}=9.95\cdot 10^{-19} J$

Converting into electronvolts,

$E=\frac{9.95\cdot 10^{-19}}{1.6\cdot 10^{-19} J/eV}=6.22 eV$ (2)

The stopping potential is the potential needed to stop the photoelectrons with maximum kinetic energy: so, the electrical potential energy corresponding to the stopping potential (V=1.93 V) must be equal to the maximum kinetic energy of the photoelectrons,

$U=q V = K$

and since the charge of the electron is

1 q = 1 e

We have

$K=(1 e)(1.93 V)=1.93 eV$ (3)

Combining (1), (2) and (3), we find the work function of the material:

$\phi = E-K=6.22 eV-1.93 eV=4.29 eV$

So, the cathode is most likely made of zinc, which has a work function of 4.3 eV.

b) The stopping potential does not change

As we said in part A), the stopping potential is proportional to the maximum kinetic energy of the photoelectrons, K.

The intensity of light is proportional to the number of photons that hit the surface of the metal. However, the energy of these photons does not depend on the intensity, but only on the frequency of the light.

Therefore, the energy of the photons (E) does not change when the intensity of light is doubled. Also, the work function $\phi$ does not change: this means that the maximum kinetic energy of the photoelectrons, K, does not change, and so the stopping potential remains the same.

6 0

3 years ago

Describe in detail how you might experimentally determine the density of a cylindrical shaped object. Explain all steps clearly

pashok25 [27]

Tbh idk I need help to

4 0

4 years ago

the process of making alloys involves _____ pure metals to remove impurities. Then the pure metals are ____ with other component

Law Incorporation [45]

I think this is the answer for the first line(Cooling ,Heating or mixing ) and for the second line is(broken down,cooled,mixed)

5 0

3 years ago

Read 2 more answers

A flatbed truck is carrying a 20.0 kg crate along a level road. the coefficient of static friction between the crate and the bed

Dahasolnce [82]

<span>3.92 m/s^2 Assuming that the local gravitational acceleration is 9.8 m/s^2, then the maximum acceleration that the truck can have is the coefficient of static friction multiplied by the local gravitational acceleration, so 0.4 * 9.8 m/s^2 = 3.92 m/s^2 If you want the more complicated answer, the normal force that the crate exerts is it's mass times the local gravitational acceleration, so 20.0 kg * 9.8 m/s^2 = 196 kg*m/s^2 = 196 N Multiply by the coefficient of static friction, giving 196 N * 0.4 = 78.4 N So we need to apply 78.4 N of force to start the crate moving. Let's divide by the crate's mass 78.4 N / 20.0 kg = 78.4 kg*m/s^2 / 20.0 kg = 3.92 m/s^2 And you get the same result.</span>

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3 years ago

Someone pushes on a rock and measures the net force acting on it is 147 N and acceleration to be 7.5m/s2.What is the weight of t

kogti [31]

Some1 pushes u and then u defend your self

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3 years ago