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notsponge [240]

3 years ago

8

Calculate the minimum amount of energy, in joules, required to completely melt 145 g of silver initially at 22.0°C. The melting

point of silver is at 962°C. Its specific heat capacity is 236 J/kg·K and its latent heat of fusion is 105 kJ/kg.

1 answer:

Tcecarenko [31]3 years ago

6 0

Answer:

47391.8 J

Explanation:

Q = m c Δt

For melting, Δt = (962-22)°C

Heat required to attain melting point = 145 x 10 ⁻³ x 236 x 940 =

= 32166.8 J

Heat required to melt at melting point = m L , L is latent heat of fusion.

= 145 x 10⁻³ x 105 x 10³ = 15225 J

Total energy required = 47391.8 J

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The angular momentum of a flywheel having a rotational inertia of 0.140 kg ·m2 about its central axis decreases from 3.00 to 0.8

Rasek [7]

Answer

given,

I = 0.140 kg ·m²

decrease from 3.00 to 0.800 kg ·m²/s in 1.50 s.

a) $\tau = \dfrac{\Delta L}{\Delta t}$

$\tau = \dfrac{0.8-3}{1.5}$

τ = -1.467 N m

b) angle at which fly wheel will turn

$\theta= \omega t +\dfrac{1}{2}\alpha t^2$

$\theta= \dfrac{L}{I} t +\dfrac{1}{2}\dfrac{\tau}{I}t^2$

$\theta= \dfrac{3}{0.14}\times 1.5+\dfrac{1}{2}\dfrac{-1.467}{0.14}\times 1.5^2$

θ = 20.35 rad

c) work done on the wheel

W = τ x θ

W = -1.467 x 20.35 rad

W = -29.86 J

d) average power of wheel

$P_{av} =-\dfrac{W}{t}$

$P_{av} =-\dfrac{(-29.86)}{1.5}$

$P_{av} =19.91\ W$

7 0

3 years ago

Read 2 more answers

An ion accelerated through a potential difference of 115 V experiences an increase in kinetic energy of 7.37 x 1017 J. Calculate

riadik2000 [5.3K]

Answer: $6.408(10)^{-19} C$

Explanation:

This problem can be solved by the following equation:

$\Delta K=q V$

Where:

$\Delta K=7.37(10)^{-17} J$ is the change in kinetic energy

$V=115 V$ is the electric potential difference

$q$ is the electric charge

Finding $q$ :

$q=\frac{\Delta K}{V}$

$q=\frac{7.37(10)^{-17} J}{115 V}$

Finally:

$q=6.408(10)^{-19} C$

4 0

3 years ago

A sample of an ideal gas is in a tank of constant volume. The sample absorbs heat energy so that its temperature changes from 33

Anuta_ua [19.1K]

Answer:

$\frac{v_{2}}{v_{1}}=2$ .

Explanation:

The average kinetic energy per molecule of a ideal gas is given by:

$\bar{K}=\frac{3k_{B}T}{2}$

Now, we know that $\bar{K} = (1/2)m\bar{v}^{2}$

Before the absorption we have:

$(1/2)m\bar{v_{1}}^{2}=\frac{3k_{B}T_{1}}{2}$ (1)

After the absorption,

$(1/2)m\bar{v_{2}}^{2}=\frac{3k_{B}T_{2}}{2}$ (2)

If we want the ratio of v2/v1, let's divide the equation (2) by the equation (1)

$\frac{v_{2}^{2}}{v_{1}^{2}}=\frac{T_{2}}{T_{1}}$

$\frac{v_{2}}{v_{1}}=\sqrt{\frac{T_{2}}{T_{1}}}$

$\frac{v_{2}}{v_{1}}=\sqrt{\frac{1340}{335}}$

$\frac{v_{2}}{v_{1}}=\sqrt{4}$

Therefore the ratio will be $\frac{v_{2}}{v_{1}}=2$

I hope it helps you!

4 0

3 years ago

Read 2 more answers

Elena-2011 [213]

Answer:

Option D.

Data; changing attitudes, beliefs, or values

Explanation:

When a speaker adds statistical data to prove the point, the audience's perception about things changes since the data implies that research has been conducted hence reliable. Consequently, the attitude of people and beliefs may change when such data is presented to them. Therefore, option D is correct.

3 0

3 years ago

Help me plz science middle school

elena55 [62]

The correct answer is A. He created a way of naming organisms based on genus and species

Explanation:

Carl Linnaeus created a simple but precise system for naming organisms of any species and kind. This system was known as binomial nomenclature and the names of organisms depend on two main elements: the genus and the species. The first element is a broad category that covers species with a common origin, and the second one is the species, which describes organisms that can reproduce and share many common features including DNA sequence. According to this, the correct answer is A.

3 0

3 years ago