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timofeeve [1]
1 year ago
13

A charged cell phone has chemical energy stored in its battery. As you use your phone, the amount of chemical energy in the batt

ery decreases. Why is this not a violation of the first law of thermodynamics?
Physics
1 answer:
Lunna [17]1 year ago
6 0

Answer:

Because the chemical energy is converted to electrical enegy in the cell phone

Explanation:

This set up is not a voilation of the first law of thermodynamics because the chemical energy is not lost, it is only being transformed into electrical energy.

According to the first law of thermodynamics "energy is neither created nor destroyed but transformed from one form to another".

  • In a charged cell phone, the chemical energy is being transformed to electrical energy as you use it.
  • A phone cannot directly be powered with chemical energy.
  • The energy transformation to electrical energy makes it possible to use the phone.
  • In this process no energy is lost nor created. But simply, energy is transformed.
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In an experiment, students release a block from rest at the top of an inclined plane. The block slides down the plane through a
mote1985 [20]

Answer:

B) Friction

Explanation:

The main source of error is the omission of the effect from friction between block and incline, which is directly proportional to the mass of the block. The force of gravity is constant. The friction force dissipates part of the gravitational potential energy, generating a final speed less than calculated under the consideration of a conservative system. Air resistance is neglected at low speeds like this case.

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What best describes myotibrils
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2 years ago
A mover pushes a 255 kg piano
faust18 [17]

Answer:

0.495 ms^{-2}

Explanation:

According to the newton's second law of motion we can apply F=ma hear

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(assume the piano is moving left side )

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7 0
2 years ago
A radioactive substance decays exponentially. A scientist begins with 200 milligrams of a radioactive substance. After 17 hours,
lianna [129]

75.17 mg of the radioactive substance will remain after 24 hours.

Answer:

Explanation:

Any radioactive substance will obey the exponential decay behavior. So according to this behavior, any radioactive substance will be decaying in terms of exponential form of disintegration constant and Time.

Disintegration constant is the rate of decay of radioactive elements. It can be measured using the half life time of the radioactive element .While half life time is the time taken by any radioactive element to decay half of its concentration. Like in this case, at first the scientist took 200 mg then after 17 hours, it got reduced to 100 g. So the half life time of this element is 17 hours.

Then Disintegration constant = 0.6932/Half Life time

Disintegration constant = 0.6932/17=0.041

Then as per the law of disintegration constant:

N = N_{0}e^{-xt}

Here N is the amount of radioactive element remaining at time t and N_{0} is the initial amount of sample, x is the disintegration constant.

So here, N_{0} = 200 mg, x = 0.041 and t = 24 hrs.

N = 200 ×e^{-24*0.041} =75.17 mg.

So 75.17 mg of the radioactive substance will remain after 24 hours.

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1 year ago
Why are we unable to work long without food
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Answer:

Without food your not able to produce energy thats why you cannot work so long

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