How much heat is needed to raise the temperature of 9g of water by 17oC?

The noble gases neon (atomic mass 20.1797 u) and krypton (atomic mass 83.798 u) are accidentally mixed in a vessel that has a te

vagabundo [1.1K]

Answer:

(a) Kav Ne = Kav Kr = 7.29x10⁻²¹J

(b) v(rms) Ne= 659.6m/s and v(rms) Kr= 323.7m/s

Explanation:

(a) According to the kinetic theory of gases the average kinetic energy of the gases can be calculated by:

$K_{av} = \frac{3}{2}kT$ (1)

where $K_{av}$ : is the kinetic energy, k: Boltzmann constant = 1.38x10⁻²³J/K, and T: is the temperature

From equation (1), we can calculate the average kinetic energies for the krypton and the neon:

$K_{av} = \frac{3}{2} (1.38\cdot 10^{-23} \frac{J}{K})(352.2K) = 7.29\cdot 10^{-21}J$

(b) The rms speeds of the gases can be calculated by:

$K_{av} = \frac{1}{2}mv_{rms}^{2} \rightarrow v_{rms} = \sqrt \frac{2K_{av}}{m}$

where m: is the mass of the gases and $v_{rms}$ : is the root mean square speed of the gases

For the neon:

$v_{rms} = \sqrt \frac{2(7.29 \cdot 10^{-21}J)}{20.1797 \frac{g}{mol} \cdot \frac {1mol}{6.022\cdot 10^{23}molecules} \cdot \frac{1kg}{1000g}} = 659.6 \frac{m}{s}$

For the krypton:

$v_{rms} = \sqrt \frac{2(7.29 \cdot 10^{-21}J)}{83.798 \frac{g}{mol} \cdot \frac {1mol}{6.022\cdot 10^{23}molecules} \cdot \frac{1kg}{1000g}} = 323.7 \frac{m}{s}$

Have a nice day!

3 0

2 years ago

ALWAYS use significant figure rules. Remember that these rules apply to all numbers that are measurements.

natali 33 [55]

Answer:

Well I'm going to go with A.

Explanation:

As per the question the mass of the boy is 40 kg.

The boy sits on a chair.

We are asked to calculate the force exerted by the boy on the chair at sea level.

The force exerted by boy on the chair while sitting on it is nothing else except the force of gravity of earth i.e the weight of the body .The direction of that force is vertically downward.

At sea level the acceleration due to gravity g = 9.8 m/s^2

Therefore, the weight of the boy [m is the mass of the body]

we have m = 40 kg.

Therefore, w = 40 kg ×9.8 m/s^2

=392 N kg m/s^2

= 392 N

392 is not an option but I'm guessing you can round down 2 .to option A. 390...?

8 0

3 years ago

The structure of a main sequence star like our sun can hold for a long time because

svp [43]

Answer: B

The immense volume of matter

Explanation:

Stars are formed by cloud and dust, draw together by gravity.

But the longevity of a main sequence star lives depends on how massive it is. An enormous massive star burns faster due to its enormous material it contains and higher core temperatures caused by greater gravitational forces. While a less massive star will burn slowly and stick around the sun for a very long period. The structure of a main sequence star like our sun can therefore hold for a long time because of the immense volume of matter of star.

5 0

2 years ago

A protester carries his sign of protest, starting from the origin of an xyz coordinate system, with the xy plane horizontal. He

OverLord2011 [107]

Answer:

Part A:

$Displacement\ vector= -40\hat i+20\hat j+25\hat k$

Part B:

Magnitude of displacement=44.721359 m

Explanation:

Given Data:

40 m in negative direction of the x axis

20 m perpendicular path to his left (considering +ve y direction)

25 m up a tower (Considering +ve z direction)

Required:

In unit-vector notation, what is the displacement of the sign from start to end.
The magnitude of the displacement of the sign from start to this new end=?

Solution:

Part A:

$Displacement= (0-40)\hat i+(0+20)\hat j+(0+25)\hat k\\Displacement= -40\hat i+20\hat j+25\hat k$

where:

i,j,k are unit vectors

Part B:

Sign falls to foot of tower so z=0

$Displacement= -40\hat i+20\hat j+0\hat k$

Magnitude of displacement:

$Magnitude\ of\ displacement=\sqrt{(-40)^2+(20)^2+0^2} \\Magnitude\ of\ displacement=44.721359\ m$

6 0

2 years ago

Suppose you increase your walking speed from 1 m/s to 3 m/s in a period of 1 s. What is your acceleration?

Effectus [21]

Answer:

2 m/s²

Explanation:

a = Δv / Δt

a = (3 m/s − 1 m/s) / 1 s

a = 2 m/s²

5 0

2 years ago