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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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A 1000 kilogram empty cart moving with a speed of 6.0 meters per second is about to collide with a stationary loaded cart having
yuradex [85]

Explanation:

a) m1u1 + m2u2 = v(m1+m2)

1000×6 + 5000×0 = v(1000+5000)

6000 + 0 = 6000v

v = 6000/6000

v = 1 m/s

b) ½ ×(m1+m2)v²

= 0.5×6000×1²

=0.5×6000

=3000J

=3KJ

c) solve for b4 collision and compare

Goodluck

3 0
2 years ago
Read 2 more answers
Question #2
Contact [7]

Answer:

Distance 20 km and Displacement 0 km

His displaceent is 0 km because he ends his walk where he started. The total distance of his walk is 20 km because he walks 10 km to the store + 10km back home.

8 0
2 years ago
What is the binding energy (in J/mol or kJ/mol) of an electron in a metal whose threshold frequency for photoelectrons is 2.50 u
Aleksandr-060686 [28]

Answer:

binding energy is 99771 J/mol

Exlanation:

given data

threshold frequency = 2.50 ×  10^{14} Hz

solution

we get here binding energy using threshold frequency of the metal that is express as

E=h\nu_{o}    ..................1

here E is the energy of electron per atom E=\frac{x}{N}  and h is plank constant i.e. 6.626\times10^{-34} Js  and x is  binding energy

and here N is the Avogadro constant = 6.023\times10^{23}

so E will \frac{x}{6.023\times10^{23}}  

E = 3.19\times10^{-19}  J  

so put value in equation 1 we get

\frac{x}{6.023\times10^{23}} = 2.50 ×  10^{14} × 6.626\times10^{-34} Js  

solve it we get

x = 99770.99

so  binding energy is 99771 J/mol

4 0
1 year ago
On a cold winter day when the temperature is −20∘C, what amount of heat is needed to warm to body temperature (37 ∘C) the 0.50 L
vlabodo [156]

Answer:

75.6J

Explanation:

Hi!

To solve this problem we must use the first law of thermodynamics that states that the heat required to heat the air is the difference between the energy levels of the air when it enters and when it leaves the body,

Given the above we have the following equation.

Q=(m)(h2)-(m)(h1)

where

m=mass=1.3×10−3kg.

h2= entalpy at 37C

h1= entalpy at -20C

Q=m(h2-h1)

remember that the enthalpy differences for the air can approximate the specific heat multiplied by the temperature difference

Q=mCp(T2-T1)

Cp= specific heat of air = 1020 J/kg⋅K

Q=(1.3×10−3)(1020)(37-(-20))=75.6J

4 0
1 year ago
You are testing a new amusement park roller coaster with an empty car with a mass of 130 kg. One part of the track is a vertical
vlada-n [284]

Answer:

Work done by friction along the motion is given as

W_f = -5857.8 J

Explanation:

As per work energy theorem we can say

Work done by all forces = change in kinetic energy of the system

so here car is moving from bottom to top

so here the change in kinetic energy is total work done on the car

so here we will have

W_f + W_g = \frac{1}{2}m(v_f^2 - v_i^2)

W_f - mgH = \frac{1}{2}m(v_f^2 - v_i^2)

now plug in all data in it

W_f - (130)(9.81)(2\times 12) = \frac{1}{2}(130)(8^2 - 25^2)

W_f = 30607.2 - 36465

W_f = -5857.8 J

6 0
1 year ago
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