What is Mach 2 in miles per hour?

How much heat is evolved when 1234 g of water condenses to a liquid at 100.°c?

lbvjy [14]

During the phase transition vapour --> liquid water, the temperature of the water does not change; the molecules of water release heat and the amounf of heat released is equal to
$Q=mL_e$
where
m is the mass of the water
$L_e$ is the latent heat of evaporation.

For water, the latent heat of evaporation is $L=2257 kJ/kg$ , while the mass of the water is
$m=1234 g=1.234 kg$

so, the amount of heat released in the process is
$Q=mL_e = (1.234 kg)(2257 kJ/kg)=2785 kJ$

6 0

3 years ago

Which statement best describes air pressure at high altitudes? (Points : 3)

WARRIOR [948]

Air pressure decreases as altitude increases. this is because air pressure is caused by the gravity of earth, the gravity pulls on the air, compacting it and making a pressure.
But as we go higher, gravity decreases, causing less pull on the air resulting in less air pressure.<span />

5 0

3 years ago

Read 2 more answers

Time Intervals in Ice Ages

stepladder [879]

It started off with 68% less than it did at the peak, and later created a void and melted the remainder of the ice at about 92%

8 0

3 years ago

The thermal energy in a heat engine is used to move a piston. Which best describes why this is possible?

Natali [406]

Answer:

The increase in thermal energy results in an increase in pressure.

Explanation:

The increase in entropy is directly related to the increase in temperature. So the thermal energy in heat engine increases the temperature of that surrounding.
Higher temperature means the kinetic energy of particles is also higher, their vibration is increasing. So it increases the pressure (ideal gas law).
In this way the increment in the thermal energy in heat engine moves piston by increasing the pressure.

6 0

2 years ago

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Um objeto de 4cm de altura está a 30cm de um espelho côncavo, cujo raio de curvatura tem valor absoluto de 20cm.

Shkiper50 [21]

a) The distance of the image from the mirror is 15 cm

b) The size of the image is -2 cm (inverted)

Explanation:

a)

We can solve this first part of the problem by applying the mirror equation:

$\frac{1}{f}=\frac{1}{p}+\frac{1}{q}$