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sladkih [1.3K]
2 years ago
12

A rotating paddle wheel is inserted in a closed pot of water. The stirring action of the paddle wheel heats the water. During th

e process, 30 kJ of heat is transferred to the water and 5 kJ is lost to the surrounding air. The paddle wheel work amounts to 500 J. Determine the final energy of the system if its initial energy is 10 kJ.
Physics
1 answer:
fgiga [73]2 years ago
3 0

Answer:

the final energy of the system is 35.5 kJ.

Explanation:

Given;

initial energy of the system, E₁ = 10 kJ

heat transferred to the system, q₁  30 kJ

Heat lost to the surrounding, q₂ = 5kJ

heat gained by the system, Q = q₁ - q₂ = 30 kJ - 5kJ = 25 kJ

work done on the system, W = 500 J = 0.5 kJ

Apply first law of thermodynamic,

ΔU = Q + W

where;

ΔU  is change in internal energy

Q is the heat gained by the system

W is work done on the system

ΔU = 25kJ + 0.5 kJ

ΔU = 25.5 kJ

The final energy of the system is calculated as;

E₂ = E₁ + ΔU

E₂ = 10 kJ + 25.5 kJ

E₂ =  35.5 kJ.

Therefore, the final energy of the system is 35.5 kJ.

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To test the performance of its tires, a car
Rom4ik [11]

The coefficient of static friction is 0.222

Explanation:

In order for the car to remain in circular motion, the frictional force must be able to provide the necessary centripetal force. Therefore, the car will start skidding when the two forces are equal:

\mu mg=m\frac{v^2}{r}

where the term on the left is the frictional force, while the term on the right is the centripetal force, and where

\mu is the coefficient of static friction

m is the mass of the car

g is the acceleration of gravity

v is the speed of the car

r is the radius of the track

In this problem, we have:

r = 564 m

v = 35 m/s

g=9.8 m/s^2

And re-arranging the equation for \mu, we can find the coefficient of static friction:

\mu = \frac{v^2}{gr}=\frac{35^2}{(9.8)(564)}=0.222

Learn more about friction:

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brainly.com/question/5884009

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5 0
3 years ago
27 degrees to kelvin, 20 dg to milligrams, and 3 to decimeters.
Gala2k [10]
K = C + 273, so 27°C = 27+273 = 300 K

1 dg = 100 mg, so 20 dg = 20×100 = 2,000 mg
7 0
3 years ago
A reasonable estimate of the moment of inertia of an ice skater spinning with her arms at her sides can be made by modeling most
Oxana [17]

Answer:

A)  I_{total} = 1.44 kg m², B) moment of inertia must increase

Explanation:

The moment of inertia is defined by

     I = ∫ r² dm

For figures with symmetry it is tabulated, in the case of a cylinder the moment of inertia with respect to a vertical axis is

      I = ½ m R²

A very useful theorem is the parallel axis theorem that states that the moment of inertia with respect to another axis parallel to the center of mass is

    I = I_{cm} + m D²

Let's apply these equations to our case

The moment of inertia is a scalar quantity, so we can add the moment of inertia of the body and both arms

      I_{total}=I_{body} + 2 I_{arm}

       I_{body} = ½ M R²

The total mass is 64 kg, 1/8 corresponds to the arms and the rest to the body

       M = 7/8 m total

       M = 7/8 64

       M = 56 kg

The mass of the arms is

      m’= 1/8 m total

      m’= 1/8 64

      m’= 8 kg

As it has two arms the mass of each arm is half

     m = ½ m ’

     m = 4 kg

The arms are very thin, we will approximate them as a particle

    I_{arm} = M D²

Let's write the equation

     I_{total} = ½ M R² + 2 (m D²)

Let's calculate

    I_{total} = ½ 56 0.20² + 2 4 0.20²

    I_{total} = 1.12 + 0.32

    I_{total} = 1.44 kg m²

b) if you separate the arms from the body, the distance D increases quadratically, so the moment of inertia must increase

6 0
3 years ago
A mass on a spring vibrates in simple harmonic motion at an amplitude of 8.0 cm. If the mass of the object is 0.20 kg and the sp
Dmitry [639]

Answer:

Frequency, f = 3.73Hz

Explanation:

The frequency of a simple harmonic 6is given by:

f = w/2pi

But w= Sqrt( k/m)

Where k is the spring constant

And m is the mass

Given:

Mass=0.20kg

Spring constant, k=130N/m

w= Sqrt(130/0.20)

w= Sqrt(650)

w= 25.50 m

Frequency, f = w/2pi

f = 25.50/(2×3.142)

f = 3.73Hz

5 0
3 years ago
A force F~ = Fx ˆı + Fy ˆ acts on a particle that
Hatshy [7]

Answer:

W = 46 J

Explanation:

We need to find the angle between the two vectors Force vector and displacement vector.

First we will find the angle α of the force vector

tan\alpha =\frac{1}{8} \\\\\\alpha =7.125 deg\\

Then we find the angle β of the displacement vector

tan\beta=\frac{2}{6} \\\\beta = 18.43 deg\\

With these two angles we can find the angle between the two vectors

∅ = α + β = 25.56 deg

The definition of work is given by the expression

W=F*d*cos (theta)

The absolute value of F will be:

F=\sqrt{8^{2}+1^{2}  } \\F= 8.06 N

The absolute value of d will be:

d=\sqrt{(6 )^{2}+(2)^{2}  } \\d= 6.32m\\

Now we have:

W=8.06*6.32*cos(25.56)\\W=46 J

4 0
3 years ago
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