Answer: 9
Explanation:
Kinetic energy is the energy possessed by a moving object. It is measured in joules, and depends on the mass (m) of the object and the speed (v) by which it moves i.e K.E = 1/2 x mass x velocity^2
So, car is traveling 120 km/h
KE = 1/2x m x (120 km/h)^2
KE = 0.5 x m x 14400
KE1 = 7200m
So, car is traveling 40 km/h
KE = 1/2x m x (40 km/h)^2
KE = 0.5 x m x 1600
KE2 = 800m
Now, divide the value of kinetic energy obtained during 120 km/h by that obtained during 40 km/h
i.e 7200m / 800m
= 9
Thus, the kinetic energy will be 9 times more at a speed of 120 km/h than at 40 km/h
Answer:
The four lobes of the brain are the frontal, parietal, temporal, and occipital lobes.The frontal lobe is located in the forward part of the brain, extending back to a fissure known as the central sulcus. The frontal lobe is involved in reasoning, motor control, emotion, and language.
Explanation:
<span>Waves cause erosion through the processes of impact and abrasion. </span><span>
2. c. they move up and down, but do not move forward. </span>
Yp(t) = A1 t^2 + A0 t + B0 t e(4t)
=> y ' = 2A1t + A0 + B0 [e^(4t) +4 te^(4t) ]
y ' = 2A1t + A0 + B0e^(4t) + 4B0 te^(4t)
=> y '' = 2A1 + 4B0e(4t) + 4B0 [ e^(4t) + 4te^(4t)
y '' = 2A1 + 4B0e^(4t) + 4B0e^(4t) + 16B0te^(4t)
Now substitute the values of y ' and y '' in the differential equation:
<span>y′′+αy′+βy=t+e^(4t)
</span> 2A1 + 4B0e^(4t) + 4B0e^(4t) + 16B0te^(4t) + α{2A1t + A0 + B0e^(4t) + 4B0 te^(4t) } + β{A1 t^2 + A0 t + B0 t e(4t)} = t + e^(4t)
Next, we equate coefficients
1) Constant terms of the left side = constant terms of the right side:
2A1+ 2αA0 = 0 ..... eq (1)
2) Coefficients of e^(4t) on both sides
8B0 + αB0 = 1 => B0 (8 + α) = 1 .... eq (2)
3) Coefficients on t
2αA1 + βA0 = 1 .... eq (3)
4) Coefficients on t^2
βA1 = 0 ....eq (4)
given that A1 ≠ 0 => β =0
5) terms on te^(4t)
16B0 + 4αB0 + βB0 = 0 => B0 (16 + 4α + β) = 0 ... eq (5)
Given that B0 ≠ 0 => 16 + 4α + β = 0
Use the value of β = 0 found previously
16 + 4α = 0 => α = - 16 / 4 = - 4.
Answer: α = - 4 and β = 0
With almost all substances . . .
-- when you cool them, their electrical resistance decreases.
-- If you make them even colder, their resistance decreases more.
-- If you make them even colder, their resistance decreases more.
-- If you make them even colder, their resistance decreases more.
-- If you keep making them colder, their resistance keeps decreasing,
but it never completely disappears, no matter how cold you make them.
But with a few surprising substances, called 'superconductors' . . .
-- when you cool them, their electrical resistance decreases.
-- If you make them even colder, their resistance decreases more.
-- If you make them even colder, their resistance decreases more.
-- If you make them even colder, their resistance decreases more.
-- If you keep making them colder, then suddenly, at some magic
temperature, their resistance COMPLETELY disappears. It doesn't
just become small, and it doesn't just become too small to measure.
It becomes literally totally and absolutely ZERO.
If you start a current flowing in a superconducting wire, for example,
you can connect the ends of the wire together, and the current keeps
flowing around and around in it, for months or years. As long as you
keep the loop cold enough, the current never decreases, because
the superconducting wire has totally ZERO resistance.
Did somebody say "What's this good for ? What can you do with it ?"
1). Every CT-scan machine and every MRI machine needs many
powerful magnets to do its thing. They are all electromagnets, with
coils of superconducting wire, enclosed in containers full of liquid helium.
Yes, it's complicated and expensive. But it turns out to be simpler and
cheaper than using regular electromagnets, with coils of regular plain
old copper wire, AND the big power supplies that would be needed
to keep them going.
2). Resistance in wire means that when current flows through it,
energy is lost. The long cables from the power-generating station
to your house have resistance, so energy is lost on the way from the
generating station to your house. That lost energy is energy that the
electric company can't sell, because they can't deliver it to customers.
There are plans to build superconducting cables to carry electric power
from the producers to the customers. The cables will be hollow pipes,
with liquid helium or liquid hydrogen inside to keep them cold, and
something on the outside to insulate them from the warmth outside.
Yes, they'll be complicated and expensive. But they'll have ZERO
resistance, so NO energy will be lost on its way from the generating
stations to the customers. The power companies think they can
build superconducting 'transmission lines' that will cost less than
the energy that's being lost now, with regular cables.
