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2 years ago

What is dark energy?

Physics

1 answer:

olga2289 [7]2 years ago

6 0

Explanation:

Dark Energy. Dark Energy is a hypothetical form of energy that exerts a negative, repulsive pressure, behaving like the opposite of gravity. It has been hypothesised to account for the observational properties of distant type Ia supernovae, which show the universe going through an accelerated period of expansion

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Glycerin (C3H8O3) is a nonvolatile liquid. What is the vapor pressure of a solution made by adding 154 g of glycerin to 316 mL o

garri49 [273]

Answer:

$P_{sol}=50.4\ mm.Hg$

Explanation:

According to given:

molecular mass of glycerin, $M_g=3\times 12+8+3\times 16=92\ g.mol^{-1}$

molecular mass of water, $M_w=2+16=18\ g.mol^{-1}$

∵Density of water is $0.992\ g.cm^{-3}= 0.992\ g.mL^{-1}$

∴mass of water in 316 mL, $m_w=316\times 0.992=313.5 g$

mass of glycerin, $m_g=154\ g$

pressure of mixture, $P_x=55.32\ torr= 55.32\ mm.Hg$

temperature of mixture, $T_x=40^{\circ}C$

Upon the formation of solution the vapour pressure will be reduced since we have one component of solution as non-volatile.

moles of water in the given quantity:

$n_w=\frac{m_w}{M_w}$

$n_w=\frac{313.5}{18}$

$n_w=17.42 moles$

moles of glycerin in the given quantity:

$n_g=\frac{m_g}{M_g}$

$n_g=\frac{154}{92}$

$n_g=1.674 moles$

Now the mole fraction of water:

$X_w=\frac{n_w}{n_w+n_g}$

$X_w=\frac{17.42}{17.42+1.674}$

$X_w=0.912$

Since glycerin is non-volatile in nature so the vapor pressure of the resulting solution will be due to water only.

$\therefore P_{sol}=X_w\times P_x$

$\therefore P_{sol}=0.912\times 55.32$

$P_{sol}=50.4\ mm.Hg$

7 0

2 years ago

A truck going 15 kmôŹ°€h has a head-on collision with a small car going 30 kmôŹ°€h. Which statement best describes the situation

zlopas [31]

1. e) None of the above is necessarily true.

2.d) Without knowing the mass of the boat and the sack, we cannot tell.

5 0

2 years ago

A 7.00-kg object undergoes an acceleration given by ax=3.00 and ay= 9.00 m/s2. Find (a) the components of the force acting on th

lord [1]

Answer:

66.4 N

Explanation:

From Newton's second law, F = ma

where F is the force, m is the mass and a is the acceleration.

Because the object has acceleration in two directions and the mass is constant, the force will be in two directions. The component of the forces are:

$F_x = ma_x = (7.00\text{ kg})(3.00 \text{ m/s}^2) = 21.0\text{ N}$

$F_y = ma_y = (7.00\text{ kg})(9.00 \text{ m/s}^2) = 63.0\text{ N}$

The magnitude of the resultant force is given by

$F = \sqrt{F_x^2+F_y^2}$

$F = \sqrt{(21.0\text{ N})^2+(63.0\text{ N})^2} = \sqrt{(441.0\text{ N}^2)+(3969.0\text{ N}^2)} = \sqrt{(4410\text{ N}^2)} = 66.4 \text{ N}$

7 0

2 years ago

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Gas liquids will both expand to fll their containers true or false

MrMuchimi

It Is False. Liquid will not expand to fill it's container, while gas will.

6 0

2 years ago

A passenger bus is travelling 28.0 m/s to the right when the driver applies the brakes. The bus stops in 5.00 s. What is the acc

MAVERICK [17]

Change in velocity = d(v)
d(v) = v2 - v1 where v1 = initial speed, v2 = final speed
v1 = 28.0 m/s to the right
v2 = 0.00 m/s
d(v) = (0 - 28)m/s = -28 m/s to the right

Change in time = d(t)
d(t) = t2 - t1 where t1 = initial elapsed time, t2 = final elapsed time
t1 = 0.00 s
t2 = 5.00 s
d(t) = (5.00 - 0.00)s = 5.00s

Average acceleration = d(v) / d(t)
(-28.0 m/s) / (5.00 s)
(-28.0 m)/s * 1 / (5.00 s) = -5.60 m/s² to the right

3 0

2 years ago

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