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erma4kov [3.2K]
3 years ago
13

Steel blocks A and B, which have equal masses, are at TA = 300 oC and T8 = 400 oC. Block C, with mc - 2mA, is at TC = 350 oC. Bl

ocks A and B are placed in contact, isolated, and allowed to come into equilibrium. Then they are placed in contact with block C. At that instant:a.TA = TB < TCb.TA = TB = TCc.TA = TB > TCd.TA + TB = TCe.TA - TB = TC
Physics
1 answer:
shepuryov [24]3 years ago
8 0

Answer:

b) TA = TB = TC

Explanation:

  • When put in contact each other, and isolated, both blocks will exchange heat till they reach to thermal equilibrium.
  • During this process, the body at a higher temperature, will loss heat, tat it will be gained by the other body.
  • The equilibrium condition will be reached when the following equation be met:

       \Delta Q = c_{st}* m_{A} * (T_{fin}  - T_{0A} ) = c_{st}* m_{B} * (T_{0B}  - T_{fin} )

  • Replacing by the values of T₀A = 300º C, and T₀B = 400ºC, and simplifying common terms as mA = mB, we can solve for  Tfin, as follows:

       (400 \ºC - T_{fin}) = (T_{fin} - 300 \ºC) \\ \\  2* T_{fin} = 700\ºC\\ \\ T_{fin} = 350\ºC

  • So, when both blocks reach to equilibrium, they will be at a common final temperature, 350ºC.
  • When put in contact with block C, at the same temperature, at that instant, the three blocks will have the same common temperature of 350 ºC.
  • So, option b) is the right one.
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hram777 [196]

Answer: D(t)= 50(4/5)^t

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If we start with the initial temperature difference, 50° Celsius, and keep multiplying by 4/5, this function gives us the temperature difference t minutes after the cake was put in the cooler.

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3 years ago
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A trumpet creates a sound wave that has a wave speed of 350m/s and a wavelength of 0.8 m . What is the frequency of the sound wa
ValentinkaMS [17]

Answer:

The frequency of sound wave created by trumpet is 437.5Hz

Explanation:

Given

the speed of sound wave = 350 ms^{-1}

the wavelength of sound wave = 0.8 m

the frequency of sound wave = ?

All the waves have same relationship among wavelength, frequency and speed, which is given by the equation:

v = fλ, where

v is speed of the wave

f is frequency of the wave

λ is wavelength of the wave

therefore frequency of sound wave is given by

f = v/λ

 = 350ms^{-1}/0.8m

 = 437.5s^{-1}

 = 437.5Hz (since 1 s^{-1} = 1 Hz (Hertz)

Hence the frequency of sound wave created by trumpet is 437.5Hz

7 0
3 years ago
Use Eq. cosϕ=R/Z to show that the average power delivered by the source in an L−R−C series circuit is given by Pav = I^2rmsR .
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Answer:

Explanation:

In a L C R circuit, the average power is given by

P_{av}=V_{rms}I_{rms}Cos\phi

As given in the question

CosФ = R / Z

And we know that

V_{rms}=I_{rms}\times Z

So

P_{av}=I_{rms}\times Z\times I_{rms}\times \frac{R}{Z}

P_{av}=I_{rms}^{2}\times R

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The Capacitive reactance of a 0.094uF capacitor when a frequency of 25kHz is applied is lus 68 Ohms 0.68 Ohms luf
Nana76 [90]

Answer:

Capacitive reactance of the capacitor is 68 ohms

Explanation:

It is given that,

Capacitance, C=0.094\ \mu F=0.094\times 10^{-6}\ F

Frequency, f=25\ kHz=25\times 10^3\ Hz

Capacitive reactance is given by :

X_C=\dfrac{1}{2\pi fC}

X_C=\dfrac{1}{2\pi 25\times 10^3\times 0.094\times 10^{-6}}

X_C=67.72\ \Omega

or

X_C=68\ \Omega

So, the capacitive reactance of the capacitor is 68 ohms. Hence, this is the required solution.

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3 years ago
In traveling a distance of 2.5 km between points A and D, a car is driven at 99 km/h from A to B for t seconds and 48 km/h from
Andreyy89

Answer:

d = 1.954 Km

Explanation:

given,

total distance, D = 2.5 Km

in stretch A to B =

speed = 99 Km/h = 99 x 0.278 = 27.22 m/s     time =t

in stretch B to C

time = 3.4 s

In stretch C to D

speed = 48 Km/h = 48 x 0.278 = 13.34 m/s     time =t      

we know,

distance = speed x time

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using equation of motion

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a = 4.08 m/s²

uniform deceleration is equal to 4.08 m/s²

distance traveled in BC

s = ut + \dfrac{1}{2}at^2

s = 13.34\times 3.4 + \dfrac{1}{2}\times 4.08 \times 3.4^2

s = 68.94 m

3000 = 99 \times \dfrac{1000\ t}{3600}+ 68.94 + 48\times \dfrac{1000\ t}{3600}

3000 = 27.5 t + 68.94 + 13.33 t

40.83 t = 2931.06

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distance = s x t

d = 27.22 x 71.79

d = 1954 m

d = 1.954 Km

distance between A and B is equal to 1.954 Km.

4 0
3 years ago
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