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Bond [772]
3 years ago
13

1.

Physics
1 answer:
rusak2 [61]3 years ago
7 0

Answer:

9.6

Explanation:

to convert km to miles multiply by 1.609

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The following table lists the work functions of a few commonmetals, measured in electron volts.
steposvetlana [31]

Answer:

Lithium

Explanation:

The equation for the photoelectric effect is

\frac{hc}{\lambda}= \phi + K_{max}

where

\frac{hc}{\lambda} is the energy of the incident photon, with

h being the Planck constant

c is the speed of light

\lambda is the wavelength of the photon

\phi is the work function of the metal (the minimum energy needed to extract the photoelectron from the metal)

K_{max} is the maximum kinetic energy of the emitted photoelectrons

In this problem, we have

\lambda= 190 nm = 1.9\cdot 10^{-7}m is the wavelength of the incident photon

K_{max}=4.0 eV is the maximum kinetic energy of the electrons

First of all we can find the energy of the incident photon

E=\frac{(6.63\cdot 10^{-34} Js)(3\cdot 10^8 m/s)}{1.90\cdot 10^{-7} m}=1.05\cdot 10^{-18} J

Converting into electronvolts,

E=\frac{1.05\cdot 10^{-18} J}{1.6\cdot 10^{-19} J/eV}=6.6 eV

So now we can re-arrange the equation of the photoelectric effect to find the work function of the metal

\phi = E-K_{max}=6.6 eV - 4.0 eV=2.6 eV

So the metal is most likely Lithium, which has a work function of 2.5 eV.

3 0
3 years ago
A ball is dropped from the roof of a building. the mass of the ball is 3.0 kg. what is the potential energy of the ball in the i
vitfil [10]
According to given condition there is no height(m) given from roof of building to the ground, there height given 18 m at a point above the ground.                         So, h=18m  ,                mass=3kg     ,         g=9.8m/s2                                                                      P.E=mgh                                                                                                                P.E=(3)(9.8)(18)                                                                                                      P.E=529J
                                      
6 0
3 years ago
A living thing that feeds on Another living thing and may kill it eventually is called
Murljashka [212]

Answer:

(D) parasite........................

3 0
2 years ago
A 2.7-kg block is released from rest and allowed to slide down a frictionless surface and into a spring. The far end of the spri
exis [7]

a) The speed of the block at a height of 0.25 m is 2.38 m/s

b) The compression of the spring is 0.25 m

c) The final height of the block is 0.54 m

Explanation:

a)

We can solve the problem by using the law of conservation of energy. In fact, the total mechanical energy (sum of kinetic+gravitational potential energy) must be conserved in absence of friction. So we can write:

U_i +K_i = U_f + K_f

where

U_i is the initial potential energy, at the top

K_i is the initial kinetic energy, at the top

U_f is the final potential energy, at halfway

K_f is the final kinetic energy, at halfway

The equation can be rewritten as

mgh_i + \frac{1}{2}mu^2 = mgh_f + \frac{1}{2}mv^2

where:

m = 2.7 kg is the mass of the block

g=9.8 m/s^2 is the acceleration of gravity

h_i = 0.54 is the initial height

u = 0 is the initial speed

h_f = 0.25 m is the final height of the block

v is the final speed when the block is at a height of 0.25 m

Solving for v,

v=\sqrt{u^2+2g(h_i-h_f)}=\sqrt{0+2(9.8)(0.54-0.25)}=2.38 m/s

b)

The total mechanical energy of the block can be calculated from the initial conditions, and it is

E=K_i + U_i = 0 + mgh_i = (2.7)(9.8)(0.54)=14.3 J

At the bottom of the ramp, the gravitational potential energy has become zero (because the final heigth is zero), and all the energy has been converted into kinetic energy. However, then the block compresses the spring, and the maximum compression of the spring occurs when the block stops: at that moment, all the energy of the block has been converted into elastic potential energy of the spring. So we can write

E=E_e = \frac{1}{2}kx^2

where

k = 453 N/m is the spring constant

x is the compression of the spring

And solving for x, we find

x=\sqrt{\frac{2E}{k}}=\sqrt{\frac{2(14.3)}{453}}=0.25 m

c)

If there is no friction acting on the block, we can apply again the law of conservation of energy. This time, the initial energy is the elastic potential energy stored in the spring:

E=E_e = 14.3 J

while the final energy is the energy at the point of maximum height, where all the energy has been converted into gravitational potetial energy:

E=U_f = mg h_f

where h_f is the maximum height reached. Solving for this quantity, we find

h_f = \frac{E}{mg}=\frac{14.3}{(2.7)(9.8)}=0.54 m

which is the initial height: this is correct, because the total mechanical energy is conserved, so the block must return to its initial position.

Learn more about kinetic and potential energy:

brainly.com/question/1198647

brainly.com/question/10770261

brainly.com/question/6536722

#LearnwithBrainly

5 0
3 years ago
What is the oxidation state of a hydrogen atom bound to an iron atom.?
tresset_1 [31]
the answer is rust so the answer is rust
8 0
3 years ago
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