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3 years ago

When a metal is heated, the free electrons gain _____________.

Physics

1 answer:

evablogger [386]3 years ago

5 0

<h2>Answer: C. Kinetic energy</h2>

Explanation:

Heat is energy in transit, in fact it is a transfer of thermal energy from one body to another.

So, when a metal is heated is because we have two bodies with different temperatures and thermal energy is transferred from one body to another, implying a high speed and kinetic energy in the particles involved (electrons in this case).

This is because the kinetic energy of a particle is that energy it possesses due to its movement, and according to the first principle of thermodynamics, there is a relationship between heat and movement, since the metal is composed of particles that are in motion (to a certain extent).

In this way, with the increase of the temperature of the metal, there is an increase of the kinetic energy of its free electrons with a gain of velocity (movement), therefore a gain in kinetic energy.

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A spacecraft is fueled using hydrazine (N2H4; molecular weight of 32 grams per mole [g/mol]) and carries 1640 kilograms [kg] of

Sauron [17]

Answer:

The value is $t = 689.029 \ hours$

Explanation:

From the question we are told that

The molar mass of hydrazine is $Z = 32 g/mol = \frac{32}{1000} = 0.032 \ kg/mol$

The initial temperature is $T_i = -186 ^o F = (-186-32) *\frac{5}{9} +273.15 = 152\ K$

The final temperature is $T_f = 78 ^o F = (78-32) *\frac{5}{9} +273.15 = 298.7 \ K$

The specific heat capacity is $c_h = 0.099 [kJ/(mol K)] = 0.099 *10^3 J/(mol/K)$

The power available is $P = 300 \ W$

The mass of the fuel is $m = 1640 \ kg$

Generally the number of moles of hydrazine present is

$n = \frac{m}{Z}$

=> $n = \frac{1640}{= 0.032}$

=> $n = 51250 \ mol$

Generally the quantity of heat energy needed is mathematically represented as

$Q = n * c_h * (T_f -T_i)$

=> $Q = 51250 * 0.099 *10^3 * (298.7 - 152)$

=> $Q = 7.441516913 * 10^{8} \ J$

Generally the time taken is mathematically represented as

$t = \frac{Q}{P}$

=> $t = \frac{7.441516913 * 10^{8} }{300}$

=> t = 2480505.6377 s

Converting to hours

$t = \frac{2480505.6377}{3600}$

=> $t = 689.029 \ hours$

6 0

3 years ago

An astronaut holds a rock 100 m above surface of Planet X. The rock is then thrown upwards with a sleek of 15m/s. The rock reach

Gelneren [198K]

Answer: $5 m/s^{2}$

Explanation:

This problem is related to vertical motion, and the equation that models it is:

$y=y_{o}+V_{o}sin\theta t-\frac{1}{2}gt^{2}$ (1)

Where:

$y=0m$ is the rock's final height

$y_{o}=100 m$ is the rock's initial height

$V_{o}=15 m/s$ is the rock's initial velocity

$\theta=90\°$ is the angle at which the rock was thrown (directly upwards)

$t=10 s$ is the time

$g$ is the acceleration due gravity in Planet X

Isolating $g$ and taking into account $sin(90\°)=1$ :

$g=(-\frac{2}{t^{2}})(y-y_{o}-V_{o}t)$ (2)

$g=(-\frac{2}{(10 s)^{2}})(0 m-100 m-(15 m/s)(10 s))$ (3)

$g=5 m/s^{2}$ (4) This is the acceleration due gravity in Planet X

5 0

3 years ago

A pulley has a mechanical advantage of 1.

sertanlavr [38]

Answer:

There is no mechanical advantage

Explanation:

The mechanical advantage is possible only when the force needed to lift a load is lesser than the weight of the load.

For example, is we have a mechanical advantage of 2, the force needed to lift will be 1/2 of the weight of the load, and if we have a mechanical advantage of 4, the force needed will be 1/4 of the weight of the load.

In the attached image there are clear examples of mechanical advantage with pulleys.

7 0

3 years ago

Diagram of an atom with labels

lina2011 [118]

See this. I hope you find your answer

6 0

3 years ago

A stone is dropped from the upper observation deck of a tower, 950 m above the ground. (assume g = 9.8 m/s2.) (a) find the dista

sergey [27]

<span>d = 950 m - 4.9t^2 m The distance an object moves under constant acceleration is d = 0.5at^2 where d = distance a = acceleration t = time. Since we're falling and since we're starting at 950 m above ground, the formula becomes: d = 950 m - 0.5at^2 Substituting known values, and simplifying gives us d = 950 m - 0.5*9.8 m/s^2 * t^2 d = 950 m - 4.9 m/s^2 * t^2 Since time is in seconds, we can cancel out the seconds in the units, getting d = 950 m - 4.9t^2 m</span>

8 0

3 years ago

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