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gtnhenbr [62]
4 years ago
15

The air in an inflated balloon (defined as the system) is warmed over a toaster and absorbs 130 J of heat. As it expands, it doe

s 79 kJ of work. What is the change in internal energy for the system? Express the energy in kilojoules to two significant figures.
Physics
1 answer:
Nadya [2.5K]4 years ago
8 0

Answer:

The change in internal energy for the system = - 78.87 KJ = - 79 KJ to 2 s.f

Explanation:

The first law of thermodynamics states that energy can neither be created nor destroyed but can only be transformed from one form to another.

It goes further to explain that change in the internal energy of a system (ΔU) is the sum of heat exchanged (Q) and the work done (W) by the system or on the system.

If work is done by the system, sign of work is ‘-’, if work is done on the system, the sign of work is ‘+’.

If heat is released by the system, the sign of q is ‘-’. And if heat is gained by the system, then the sign of q is ‘+’.

ΔU = Q + W

Q = 130 J

W = - 79 KJ = - 79000 J

ΔU = 130 - 79000 = - 78870 J = - 78.87 KJ = - 79 KJ

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A hot-water stream at 80 ℃ enters a mixing chamber with a mass flow rate of 0.5 kg/s where it is mixed with a stream of cold wat
rewona [7]

Answer:

\dot{m_{2}}=0.865 kg/s

Explanation:

\dot{m_1}= 0.5kg/s

from steam tables , at 250 kPa, and at

T₁ = 80⁰C ⇒ h₁ = 335.02 kJ/kg

T₂ = 20⁰C⇒ h₂ = 83.915 kJ/kg

T₃ = 42⁰C ⇒ h₃ = 175.90 kJ/kg

we know

\dot{m_{in}}=\dot{m_{out}}

\dot{m_{1}}+\dot{m_{2}}=\dot{m_{3}}

according to energy balance equation

\dot{m_{in}}h_{in}=\dot{m_{out}}h_{out}

\dot{m_{1}}h_{1}+\dot{m_{2}}h_{2}=\dot{m_{3}}h_{3}

\dot{m_{1}}h_{1}+\dot{m_{2}}h_{2}=(\dot{m_{1}}+\dot{m_{2}})h_{3}\\(0.5\times 335.02)+(\dot{m_{2}}\times 83.915)=(0.5+\dot{m_{2}})175.90\\\dot{m_{2}}=0.865 kg/s

4 0
4 years ago
Define power and describe how to determine power. (4 points)
Allushta [10]

Answer: The power is a measure of the rate at which work is done (or similarly, at which energy is transferred). The standard unit of power is Watt (1W). The power is determined by the change in energy, delta E (number of joules) and delta t, which is the time taken in seconds then: P= delta E/ delta t.

Mark me as Brainliest

Explanation:

7 0
4 years ago
5. Suppose a skydiver (mass = 75kg) is falling toward the Earth. When the skydiver is 100m above the Earth he is moving at 60m/s
Anna71 [15]

1) Gravitational potential energy: 73 500 J

2) Kinetic energy: 135 000 J

3) Mechanical energy: 208 500 J

Explanation:

1)

The gravitational potential energy of an object is the energy possessed by the object due to its position in the Earth's gravitational field, and it is given by

U=mgh

where

m is the mass of the object

g=9.8 m/s^2 is the acceleration of gravity

h is the height of the object relative to the ground

For the skydiver in this problem,

m = 75 kg is his mass

h = 100 m is his height above the Earth

Substituting, we find

U=(75)(9.8)(100)=73500 J

2)

The kinetic energy of a body is the energy due to its motion, and it is given by

K=\frac{1}{2}mv^2

where

m is the mass of the body

v is its speed

For the skydiver in this problem,

m = 75 kg is his mass

v = 60 m/s is his speed

Substituting, we find the kinetic energy

K=\frac{1}{2}(75)(60)^2=135000 J

3)

The mechanical energy of an object is the sum of the gravitational potential energy and the kinetic energy of the object:

E=U+K

where

U is the gravitational potential energy

K is the kinetic energy

For the skydiver in this problem,

U = 73,500 J is the gravitational potential energy

K = 135,000 J is the kinetic energy

Substituting, we find

E=73,500 + 135,000 = 208,500 J

Learn more about potential energy and kinetic energy:

brainly.com/question/1198647

brainly.com/question/10770261

brainly.com/question/6536722

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3 0
4 years ago
Define VR? ( plz help me)​
vlabodo [156]

Answer:

the ratio of distance travelled by effort to the distance travelled by load in the machine is called velocity ratio (VR)

8 0
3 years ago
(02.01)triangle xyz slides 2 units left and 1 unit down on the coordinate plane. if the original measure of angle x was 40 degre
andre [41]

Let us say that triangle XYZ has sides of XY, YZ, and ZX.

Each of the corners X, Y, and Z are located at their own (x, y) points.

If all of the triangle are transformed through translation by a movement of 2 units left and 1 unit down on the coordinate plane then we generate a triangle X’Y’Z’.

Then each of the corners X’, Y’ and Z’ are now located at (x – 2, y – 1) coordinates.

Since all of the corners were moved then we can also say that:

XY is congruent to X’Y’

YZ is congruent to Y’Z’

ZX is congruent to Z’X’

Since all sides are congruent, therefore all angles are also congruent.

Therefore the measure of angle x’ is equal to the measure of angle x.

 

Answer:

<span>40 degrees</span>

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4 years ago
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