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const2013 [10]
3 years ago
10

20. A semiconductor is a

Physics
1 answer:
Stells [14]3 years ago
5 0

Answer:

D. crystalline solid that conducts current under certain conditions

Explanation:

Semiconductors are crystalline solids that has the ability to conduct electrical currents but on certain conditions e.g heat. The conduction of semiconductors is less than that of conductors (metals) but more than insulators (nonmetals), hence, they are said to be intermediates of conductors and insulators in terms of electrical conductivity.

Examples of semiconductors are silicon, boron, carbon, germanium, arsenic etc.

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Katena32 [7]

Answer:

Most of us have experienced that pivotal peak of pain, anger or frustration in which we want to scream “I hate my life.” Yet, the feeling that a dark cloud has specifically settled over us and our experiences can feel pretty isolating. The truth is, no matter how singled out or overwhelmed we feel, and no matter what area we are struggling in, we are not alone.  More than half of U.S. workers are unhappy with their job.  One in 10 Americans struggles with depression. All of us have moments of utter despair. Escaping from this hopeless-seeming state may feel impossible. Yet, in reality, we are not doomed, and we are not powerless.  No matter what our circumstances, we can all learn tools to help us emerge from the darkest moments in our lives.

6 0
3 years ago
Read 2 more answers
The collision between a hammer and a nail can be considered to be approximately elastic. estimate the kinetic energy acquired by
Setler [38]

Here we can use momentum conservation as in this type of collision there is no external force on it

m_1v_{1i} + m_2v_{2i} = m_1 v_{1f} + m_2v_{2f}

now here we can say

m_1 = 10 g

v_{1i} = 0

m_2 = 550 g

v_{2i} = 3.5 m/s

now here we can say

10*0 + 550 * 3.5 = 10 v_{1f} + 550 v_{2f}

192.5 = v_{1f} + 55 v_{2f}

now by coefficient of restitution

for elastic collision we know that e = 1

v_{2f} - v_{1f} = e(v_{1i} - v_{2i})

v_{2f} - v_{1f} = 0 - 3.5

now by solving the two equation

56v_{2f} = 189

v_{2f} = 3.375 m/s

also we know that

v_{1f} = v_{2f} + 3.5 = 3.375 + 3.5 = 6.875 m/s

so final speed of the nail is 6.875 m/s


6 0
3 years ago
Read 2 more answers
A factory worker pushes a 30.0-kg crate a distance of 4.5 m along a level floor at constant velocity by pushing horizontally on
SIZIF [17.4K]

(a) 73.5 N

The velocity of the crate is constant: this means that the acceleration is zero (a=0), so according to Newton's second law

\sum F = ma

the resultant of the forces must be zero: \sum F = 0 (1)

The motion is along the horizontal direction, so we are only interested in the forces acting along this direction. There are two of them:

F, the push applied by the worker

F_f=-\mu mg, the force of friction, with \mu=0.25 being the coefficient of friction, m=30.0 kg being the mass of the crate, and g=9.8 m/s^2. The negative sign is due to the fact that the friction acts in the opposite direction to the motion. Eq.(1) then becomes

F-\mu mg=0\\F=\mu mg=(0.25)(30.0 kg)(9.8 m/s^2)=73.5 N

So, this is the force that the worker must apply.

(b) 330.8 J

The work done by the pushing force of the worker on the crate is given by:

W=Fd cos \theta

where

F = 73.5 N is the force

d = 4.5 m is the displacement

\theta=0^{\circ} is the angle between the direction of the force and the displacement (0 degrees, since they are in same direction)

Substituting, we have

W=(73.5 N)(4.5 m)(cos 0^{\circ})=330.8 J

(c) -330.8 J

To calculate the work done by friction, we apply the same formula:

W=F_f d cos \theta

where

F_f = \mu mg=(0.25)(30.0 kg)(9.8 m/s^2)=73.5 N is the magnitude of the force of friction

d = 4.5 m is the displacement

\theta=180^{\circ} is the angle between the direction of the force of friction and the displacement (it is 180 degrees since the two are into opposite directions)

Substituting, we find

W=(73.5 N)(4.5 m)(cos 180^{\circ})=-330.8 J

So, the work done by friction is negative.

(d) 0 J

As before, the work done by any force on the crate is

W=F_f d cos \theta

We notice that both gravity and normal force are perpendicular to the displacement: therefore, \theta=90^{circ}, and so

cos \theta=0

which means that the work done by both forces is zero.

(e) 0 J

The total work done on the crate is the sum of the work done by the four forces acting on it, so:

W=W_{push} + W_{friction}+W_{gravity}+W_{normal}=330.8J-330.8J+0+0=0

And this is in accordance with the work-energy theorem, which states that the variation of kinetic energy of the crate is equal to the work done on it: since the crate is moving at constant velocity, its variation of kinetic energy is zero, as well as the work done on it.

5 0
3 years ago
một nguồn điện có điện trở 0,1 ôm được mắc với điện trở 4,8 ôm thành mạch kín. Khi đó hiệu điện thế giữa hai cực của nguồn điện
zmey [24]

Answer:

good morning mam going nme mam morning mam going on in the correct

3 0
2 years ago
A rocket with a mass of 62,000 kg (including fuel) is burning fuel at the rate of 150 kg/s and the speed of the exhaust gases is
mezya [45]

Answer:

h≅ 58 m

Explanation:

GIVEN:

mass of rocket M= 62,000 kg

fuel consumption rate =  150 kg/s

velocity of exhaust gases v= 6000 m/s

Now thrust = rate of fuel consumption×velocity of exhaust gases

=6000 × 150 = 900000 N

now to need calculate time t = amount of fuel consumed÷ rate

= 744/150= 4.96 sec

applying newton's law

M×a= thrust - Mg

62000 a=900000- 62000×9.8

acceleration a= 4.71 m/s^2

its height after 744 kg of its total fuel load has been consumed

h= \frac{1}{2}at^2

h= \frac{1}{2}4.71\times4.96^2

h= 58.012 m

h≅ 58 m

4 0
3 years ago
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