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son4ous [18]
3 years ago
11

A 0.4000 kg sample of methanol at 16.0ºC is mixed with 0.4000 kg of water at 85.0ºC. Assuming no heat loss to the surroundings,

what is the final temperature of the mixture? The specific heat of methanol is 2450 J/kg•ºC, the specific heat capacity of liquid water is 4180 J/kg⋅°C
Physics
1 answer:
AVprozaik [17]3 years ago
4 0

Answer:

T_finalmix = 59.5 [°C].

Explanation:

In order to solve this problem, a thermal balance must be performed, where the heat is transferred from water to methanol, at the end the temperature of the water and methanol must be equal once the thermal balance is achieved.

Q_{water}=Q_{methanol}

where:

Q_{water}=m_{water}*Cp_{water}*(T_{waterinitial}-T_{final})

mwater = mass of the water = 0.4 [kg]

Cp_water = specific heat of the water = 4180 [J/kg*°C]

T_waterinitial = initial temperature of the water = 85 [°C]

T_finalmix = final temperature of the mix [°C]

Q_{methanol}=m_{methanol}*Cp_{methanol}*(T_{final}-T_{initialmethanol})

Now replacing:

0.4*4180*(85-T_{final})=0.4*2450*(T_{final}-16)\\142120-1672*T_{final}=980*T_{final}-15680\\157800=2652*T_{final}\\T_{final}=59.5[C]

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As viewed from above in this picture, what direction will the current be in the coil of wire that will cause the loop to rotate
Gala2k [10]

Answer:

When viewed from above, the current in the coil should point towards the top-right corner of the picture.

Explanation:

The current in this coil have only two possible directions: clockwise or counter-clockwise. However, since the diagram shows the coil from above, not from a cross-section, just saying clockwise or counter-clockwise might be ambiguous. The statement that the current is directed towards the top-right corner of the picture is equivalent to saying that when viewed from the lower-right corner of this diagram, the current in the coil is moving clockwise.

Note that at the center of this picture, the current is parallel to the magnetic field- there will be no force on the coil at that position. On the other hand, (also when viewed from above,) at the top-right corner and the lower-left corner of the coil, the current in the coil will be perpendicular to the magnetic field. That's where the force on the coil will be the strongest.

With that in mind, apply the right-hand rule to find the direction of the force on the coil in each of the two possibilities.

Assume that when viewed from above, the current is flowing towards the top-right corner of the picture. Consider the wire near the top-right corner of this coil (as viewed above on this picture.) The current will be going into the picture into the magnetic field. By the right-hand rule, the current on the wire near that point should be pointing towards the bottom of this picture. (Point fingers on the right hand in the direction of the current I. Rotate the right hand such that when curling the fingers, they point in the direction of the magnetic field B. The direction of the right thumb should now point in the direction of the force on the wire F.)

Based on the same assumption, the current in the wires near the bottom left corner of this coil will be pointing out of the picture. By the right hand rule, the magnetic force on the coil in that region should be pointing towards the top of this picture. Combing these two forces, the coil would indeed be rotating around the center of this picture in the direction shown in the diagram.

It can also be shown that if the current points towards the bottom left corner of the picture when viewed from above, the coil will be rotating about the center of this picture in the opposite direction.

7 0
3 years ago
An electric kettle. The input energy is 10 Joules. The useful output energy is heat 9
mina [271]

Answer:

Efficiency = 90 %

Wasted energy = 10 %

Explanation:

Since we have the input energy and useful output energy of the electric kettle, the only thing we are required to calculate here is its efficiency. This is gotten from

E = useful output energy/input energy × 100

E = 9/10 × 100 = 90 %

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W = wasted energy/input energy × 100

W = 1/10 × 100

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3 0
3 years ago
Physical science is the study of
const2013 [10]

The answer should be C. Both matter and energy because physical sciences are sciences concerned with the study of inanimate natural objects, including physics, chemistry, astronomy, and related subjects.

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6 0
3 years ago
A- 1000 m/s2<br> Xi-0m<br> Xf-0.75m<br> Vf-?
sleet_krkn [62]

Answer:

The final velocity of the object is,  v_{f} = 27 m/s    

Explanation:

Given,

The acceleration of the object, a = 1000 m/s²

The initial displacement of the object, x_{i} = 0 m

The final displacement of the object,  x_{f} = 0.75 m

The initial velocity of the object will be, v_{i} = o m/s

The final velocity of the object, v_{f} = ?

The average velocity of the object,

                                    v = ( x_{f} - x_{i} )/ t

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The acceleration is given by the relation

                                     a = v / t

                                   1000 m/s² = 0.75 / t²

                                            t² = 7.5 x 10⁻⁴

                                            t = 0.027 s

Using the I equation of motion,

                                  v_{f} = u + at

Substituting the values

                                   v_{f} = 0 + 1000 x 0.027

                                                           = 27 m/s

Hence, the final velocity of the object is,  v_{f} = 27 m/s          

8 0
3 years ago
A ball is thrown horizontally from the top of a tall cliff. Neglecting air drag, what vertical distance will the ball have falle
adell [148]

The relevant equation to use here is:

y = v0 t + 0.5 g t^2

where y is the vertical distance, v0 is initial velocity = 0, t is time, g = 9.8 m/s^2

 

y = 0 + 0.5 * 9.8 * 3^2

<span>y = 44.1 meters</span>

5 0
3 years ago
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