<span>D. price ceiling
</span><span>This is a government regulation that establishes a maximum price for a particular good.</span><span>
</span>
If you're listening to a sound that has a steady pitch, and suddenly the
pitch goes up, then you know that two things could have happened:
EITHER ...
-- The person or other source making the sound could have
raised the pitch of the sound being produced.
OR ...
-- The person or other source making the sound could have
started moving toward you.
OR ...
-- both.
Even if the pitch of the sound leaving the source doesn't change,
you would still hear it increase if the source starts moving toward
you. That's the so-called "Doppler effect".
Answer:
<h2><em>
12.45eV</em></h2>
Explanation:
Before calculating the work function, we must know the formula for calculating the kinetic energy of an electron. The kinetic energy of an electron is the taken as the difference between incident photon energy and work function of a metal.
Mathematically, KE = hf - Ф where;
h is the Planck constant
f is the frequency = c/λ
c is the speed of light
λ is the wavelength
Ф is the work function
The formula will become KE = hc/λ - Ф. Making the work function the subject of the formula we have;
Ф = hc/λ - KE
Ф = hc/λ - 1/2mv²
Given parameters
c = 3*10⁸m/s
λ = 97*10⁻⁹m
velocity of the electron v = 3.48*10⁵m/s
h = 6.62607015 × 10⁻³⁴
m is the mass of the electron = 9.10938356 × 10⁻³¹kg
Substituting the given parameters into the formula Ф = hc/λ - 1/2mv²
Ф = 6.63 × 10⁻³⁴*3*10⁸/97*10⁻⁹ - 1/2*9.11*10⁻³¹(3.48*10⁵)²
Ф = 0.205*10⁻¹⁷ - 4.555*10⁻³¹*12.1104*10¹⁰
Ф = 0.205*10⁻¹⁷ - 55.163*10⁻²¹
Ф = 0.205*10⁻¹⁷ - 0.0055.163*10⁻¹⁷
Ф = 0.1995*10⁻¹⁷Joules
Since 1eV = 1.60218*10⁻¹⁹J
x = 0.1995*10⁻¹⁷Joules
cross multiply
x = 0.1995*10⁻¹⁷/1.60218*10⁻¹⁹
x = 0.1245*10²
x = 12.45eV
<em>Hence the work function of the metal in eV is 12.45eV</em>
Answer:
The force exerted by the floor is 80 N.
Explanation:
Given that,
Mass of ball = 0.5 kg
Velocity= 4 m/s
Time t = 0.05 s
When the ball rebounds then the kinetic energy is
Where, m = mass of ball
v = velocity of ball
Put the value into the formula
The average force exerted by the floor on the ball = change in kinetic energy over collision time
Hence, The force exerted by the floor is 80 N.
Answer:
More than enough solar energy (8.2 million quad BTUs, 1 quad = 2.9 x1011 kWh) hits Earth's surface each year to meet all of societies' needs. Currently we use about 400 quads per year to run our society. Good building design allows passive use of sunlight to heat homes. Simple solar collectors are used to heat water and cook food. As useful as it is for these purposes, thermal energy from sunlight is still a low quality energy compared to electricity. Computers, most machinery, light bulbs, subway trains, and much more all require electricity. It is possible to turn thermal energy from the sun into electricity. In this unit we will examine how.
. We will also examine how to make electricity directly from light using the photovoltaic cells.
