Answer:
Option A
The cost of keeping the semiconductor below the critical temperature is unreasonable
Explanation:
First of all, we need to understand what superconductors are. Superconductors are special materials that conduct electrical current with almost zero resistance. This means that there is little or no need for a voltage source to be connected to them. As a matter of fact, once a superconductor is connected to a power supply, one can remove the power supply and the current will still flow.
However, most superconducts can only conduct at very low temperatures up to -200 degrees Celcius. This is because, at that temperature, their atoms and molecules are relatively settled, hence they pose little or no resistance to the flow of current.
This as you can guess is extremely difficult to do, as you will need a lot of effort to cool it to that temperature and maintain it.
This makes option a the answer:
The cost of keeping the semiconductor below the critical temperature is unreasonable.
Horizontal distance covered by a projectile is X = Vix *T
where Vix is the initial horizontal component of velocity and T is time taken by the projectile
Vix = ViCos theta
In question they said that initial velocity and angle is same on earth and moon
so Vix would remains same
now let's see about time taken T
time taken to reach the highest point
Vfy = Viy +gt
at highest point vertical velocity become zero so Vfy =0
0 = Vi Sin theta + gt
t = Vi Sintheta /g
Total time taken to land will be twice of that
On earth
Te= 2t
Te = 2Sinθ/g
on moon g is one-sixth of g(earth)
Tm = 2Sinθ/(g/6)
Tm = 6(2Sinθ/g)
Tm = 6Te
so total time taken by the projectile on moon will be six times the time taken on earth
From first equation X = Vix*T
we can see that X will also be 6 times on moon than earth
so projectile will cover 6 times distance on moon than on earth
*heat transfer energy, As it always flow from higher temperature to lower temperature till it reach the thermal equilibrium.
example: -friction.
- collisions.
- the hot cup which's hotter than your hand✋will transfer heat in your hand. and a cold piece of ice which's colder than your hand to causing the heat transfer out of your hand .
*temperature ️ depends on the move of particle and we have a different shape of motion like:
translational motion.
rotational motion.
vibrational motion.
when the temperature:
increases it has more kinetic energy and faster moving particles and the object expanded which known as (thermal expansion).
decreases it has less kinetic energy and slower moving particles.
As kinetic energy is 1/2 mV².
example: -the mercury in thermometers.
*Absolute zero :
The theoretical temperature at which substances possess no thermal energy, equal to 0 K, −273.15°C, or −459.67°F.
*specific heat "c" :
is essentially a measure of how thermally insensitive a substance is to the addition of energy.
c=Q/m∆T
where Q is energy .
note water has a higher specific heat, and lower temperature.
*conduction <em><u>example</u></em> When the stove is turned on, the skillet becomes very hot due to the conduction of heat from the burner to the skillet.
6.35x10^-4 OR 6.3x10-4 (if only one decimal number is allowed)
Answer:
a = 0.7267
, acceleration is positive therefore the speed is increasing
Explanation:
The definition of acceleration is
a = dv / dt
they give us the function of speed
v = - (t-1) sin (t² / 2)
a = - sin (t²/2) - (t-1) cos (t²/2) 2t / 2
a = - sin (t²/2) - t (t-1) cos (t²/2)
the acceleration for t = 4 s
a = - sin (4²/2) - 4 (4-1) cos (4²/2)
a = -sin 8 - 12 cos 8
remember that the angles are in radians
a = 0.7267
the problem does not indicate the units, but to be correct they must be m/s²
We see that the acceleration is positive therefore the speed is increasing
