A new piece of exercise equipment has been added to your gym, and you try it out. To use this machine, you lie horizontal on a m
1 answer:
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Answer :
The frictional force on the block from the floor and the block's acceleration are 10.45 N and 0.73 m/s².
Explanation :
Given that,
Mass of block = 3.50
Angle = 30°
Force = 15.0 N
Coefficient of kinetic friction = 0.250
We need to calculate the frictional force
Using formula of frictional force
(II). We need to calculate the block's acceleration
Using newton's second law of motion
Hence, The frictional force on the block from the floor and the block's acceleration are 10.45 N and 0.73 m/s².
a) Zinc (work function: 4.3 eV)
The equation for the photoelectric effect is:
(1)
where
is the energy of the incident photon, with
h = Planck constant
c = speed of light
= wavelength
= work function of the metal
K = maximum kinetic energy of the photoelectrons emitted
The stopping potential (V) is the potential needed to stop the photoelectrons with maximum kinetic energy: so, the corresponding electric potential energy must be equal to the maximum kinetic energy,
So we can rewrite (1) as
where we have:
V = 1.93 V
e is the electron charge
First of all, let's find the energy of the incident photon:
Converting into electronvolts,
And now we can solve eq.(1) to find the work function of the metal:
so, the metal is most likely zinc, which has a work function of 4.3 eV.
b) The stopping potential is still 1.93 V
Explanation:
The intensity of the incident light is proportional to the number of photons hitting the surface of the metal. However, the energy of the photons depends only on their frequency, so it does not depend on the intensity of the light. This means that the term E in eq.(1) does not change.
Moreover, the work function of the metal is also constant, since it depends only on the properties of the material: so is also constant in the equation. As a result, the term (eV) must also be constant, and therefore V, the stopping potential, is constant as well.