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3 years ago

How many joules of heat are absorbed to raise the temperature of 435 grams of water at 1 atm from 25°c to its boiling point?

Physics

1 answer:

Simora [160]3 years ago

4 0

<h2>Answer: 136.6 kJ </h2>

Explanation:

The amount of heat $Q$ absorbed in the temperature variation of a material is:

$Q=m. c. \Delta T$ (1)

Where:

$m=435g$ is the mass of water

$c$ is the specific heat of the element. In the case of <u>water</u> $c=1 cal/g\°C$

$\Delta T$ is the variation in temperature, which in this case is $\Delta T=100\°C-25\°C=75\°C$

(The boiling point of water at the pressure of 1 atm is $100\°C$ )

Rewriting equation (1) with the known values:

$Q=(435g)(1 cal/g\°C)(75\°C)$

(2)

$Q=32625 cal$ (3)

Nevertheless, we are asked to find this value in Joules. So, we have to convert this 32625 calories to Joules, knowing the following:

$1 cal=4.187 J$ (4)

Hence:

$Q=32625 cal=136600.875 J=136.6kJ$

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3 years ago

A magnetic field of 37.2 t has been achieved at the mit francis bitter national magnetic laboratory. Find the current needed to

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Answer:

Here is the complete question:

https://www.chegg.com/homework-help/questions-and-answers/magnetic-field-372-t-achieved-mit-francis-bitter-national-magnetic-laboratory-find-current-q900632

a) Current for long straight wire $=3.7\ MA$

b) Current at the center of the circular coil $=2.48\times 10^{5}\ A$

c) Current near the center of a solenoid $236.8\ A$

Explanation:

⇒ Magnetic Field due to long straight wire is given by (B),where $B=\frac{\mu\times I}{2\pi(r) },so\ I=\frac{B\ 2\pi(r)}{\mu}$

$\mu=4\pi \times 10^{-7}\ \frac{henry}{m}$

Plugging the values,

Conversion $1\times 10^6 A = 1\ MA$ ,and $2cm=\frac{2}{100}=0.02\ m$

$I=\frac{37.2\times \ 2\pi(0.02)}{4\ \pi \times (10^{-7})}=3.7\ MA$

⇒Magnetic Field at the center due to circular coil (at center) is given by, $B=\frac{\mu\times I (N)}{2(a)}$

So $I= \frac{2B(a)}{\mu\ N} = \frac{2\times 37.2\times 0.42}{4\pi\times 10^{-7}\times 100}=2.48\time 10{^5}\ A$

⇒Magnetic field due to the long solenoid, $B=\mu\ nI=\mu (\frac{N}{l})I$

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3 years ago

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Using analogies, the energy of the roller coaster at point E can be compared to a falling fruit from a tree which falls onto a pavement and is the rolling towards the floor. Point E can be compared to the midpoint of the fall of the fruit.

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2 years ago

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Complete question:

Resistor is made of a very thin metal wire that is 3.2 mm long, with a diameter of 0.4 mm. What is the electric field inside this metal resistor? If the potential difference due to electric field between the two ends of the resistor is 10 V.

Answer:

The electric field inside this metal resistor is 3125 V/m

Explanation:

Given;

length of the wire, L = 3.2 mm = 3.2 x 10⁻³ m

diameter of the wire, d = 0.4 mm = 0.4 x 10⁻³ m

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The electric field inside this metal resistor is given by;

ΔV = EL

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