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Setler [38]
3 years ago
6

Calculate the amount of heat absorbed when 70 mL of water is heated from 30°C to 70°C. The specific heat of liquid water is 4.18

4 J/g °C. The density of water is about 1 g/mL. Report your answer in kJ to one decimal place.
Physics
1 answer:
Annette [7]3 years ago
3 0

Answer:

the heat absorbed by water is Q=11715.2 J

Explanation:

the amount of heat absorbed is

Q = m * c * (T - Ti)

where

Q= heat absorbed by water

m = mass f water heated

c = specific heat of water

T= final temperature , Ti= inicial temperature

also we know that the mass is related with the density through

density = mass/volume

d = m / V → m = d * V

replacing m in the heat equation

Q = m * c * (T - Ti) =  d * V * c * (T - Ti)

replacing values

Q = d * V * c * (T - Ti) = 1 g/ml * 70 ml * 4.184 J/g°C * (70°C - 30°C) = 11715.2 J

Note:

we assume

- constant density of the water between 30° and 70°

- constant specific heat of water between 30° and 70°

- the water has no impurities

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Dmitrij [34]
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<span>d = 20 cm = 0.2 m </span>
<span>r = d/2 = 0.1 m </span>

<span>A = pi(r^2) </span>
<span>A = 3.14159265(.1^2) </span>
<span>A = 0.0314159265 m^2 </span>

<span>p = F/A </span>
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8 0
3 years ago
Read 2 more answers
An uncharged series RC circuit is to be connected across a battery. For each of the following changes, determine whether the tim
slavikrds [6]

a) Increase

b) Unchanged

c) Increase

Explanation:

a)

The charge on a capacitor charging in a RC circuit connected to a battery follows the exponential equation:

Q(t)=Q_0 (1-e^{-\frac{t}{RC}})

where

Q_0 = CV is the final charge stored in the capacitor, where C is the capacitance and V is the voltage of the battery

t is the time

R is the resistance of the circuit

The capacitor reaches 90% of its final charge when

Q(t)=0.90Q_0

Substituting and re-arranging the equation, we find:

0.90Q_0 = Q_0(1-e^{-\frac{t}{RC}})\\0.90=1-e^{-\frac{t}{RC}}\\e^{-\frac{t}{RC}}=0.10\\-\frac{t}{RC}=ln(0.10)\\t=-RCln(0.10)=2.30RC

We see that if we double the RC constant, then (RC)'=2(RC)

So the time taken will double as well:

t'=2.30(RC)'=2.30(2RC)=2(2.30RC)=2t

So, the answer is "increase"

b)

In this second part, the battery voltage is doubled.

According to the equation written in part a),

Q_0 =CV

this means also that the final charge stored on the capacitor will also double.

However, the equation that gives us the time needed for the capacitor to reach 90% of its full charge is

t=2.30 RC

We see that this equation does not depend at all on the voltage of the battery.

Therefore, if the battery voltage is doubled, the final charge on the capacitor will double as well, but the time needed for the capacitor to reach 90% of its charge will not change.

So the correct answer is

"unchanged"

c)

In this case, a second resistor is added in series with the original resistor of the circuit.

We know that for two resistors in series, the total resistance of the circuit is given by the sum of the individual resistances:

R=R_1+R_2

Since each resistance is a positive value, this means that as we add new resistors, the total resistance of the circuit increases.

Therefore in this problem, if we add a resistor in series to the original circuit, this means that the total resistance of the circuit will increase.

The time taken for the capacitor to reach 90% of its final charge is still

t=2.30 RC

As we can see, this time is directly proportional to the resistance of the circuit, R: therefore, if we add a resistor in series, the resistance of the circuit will increase, and therefore this time will increase as well.

So the correct answer is

"increase"

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Natalka [10]
The least number of component of a vector quantity is two. These are the x-component and the y-component. 

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From the equation, it can be noted that if we let Vx equal to zero,
              RV = Vy

Similarly, if we let Vy be equal to zero then,
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Sheila uses a 45N force on her bowling ball across a 15m lane. What work did she do on the bowling ball? Show your work.​
Maurinko [17]

Answer:

675J

Explanation:

Given parameters:

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Distance  = 15m

Unknown:

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Solution:

Work done by a body is the amount of force applied to make a body move through a distance;

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6 0
2 years ago
2. Suppose that a parallel-plate capacitor has circular plates with radius R = 30 mm and a plate separation of d = 5.0 mm. Suppo
seropon [69]

Answer:

The maximum value of the induced magnetic field is 2.901\times10^{-13}\ T.

Explanation:

Given that,

Radius of plate = 30 mm

Separation = 5.0 mm

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Suppose the maximum potential difference is 100 V and r= 130 mm.

We need to calculate the angular frequency

Using formula of angular frequency

\omega=2\pi f

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\omega=2\times\pi\times60

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We need to calculate the maximum value of the induced magnetic field that occurs at r = R

Using formula of magnetic filed

B_{max}=\dfrac{\mu_{0}\epsilon_{0}R^2\timesV_{max}\times\omega}{2rd}

Where, R = radius of plate

d = plate separation

V = voltage

Put the value into the formula

B_{max}=\dfrac{4\pi\times10^{-7}\times8.85\times10^{-12}\times(30\times10^{-3})^2\times100\times376.9}{2\times130\times10^{-3}\times5.0\times10^{-3}}

B_{max}=2.901\times10^{-13}\ T

Hence, The maximum value of the induced magnetic field is 2.901\times10^{-13}\ T.

7 0
3 years ago
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