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3 years ago

How much heat is released when 35kg of water freezes?

1 answer:

3 0

You need an additional point of data here: the enthalpy of fusion, or conversely the enthalpy of melting (they differ only by their sign). For water (or ice) that value is gotten from sources such as the internet

ΔH°(fus) = 6.01 kJ/mole 

Since you have 35 000g, how many moles do you have? 
Moles H2O = 35000 g/(18.015 g/mole) = 1942.8 moles

So, take that ΔH°(fus) in kJ/mole, multiply by the number of moles, and there ya go!

6.01 x 1942.8 = 11,676 kJ of energy is released

Hope I helped!! xx

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Which statements accurately describe mechanical waves

AleksAgata [21]

Answer:

Explanation:

so a mechanical wave transfers energy through a medium but unlike other waves that move through very long distances

the distance of the mechanical wave is different

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3 years ago

What's the definition energy?

Anit [1.1K]

Energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object.

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3 years ago

A sound wave of 70 cm travels 840 m in 2.5 sec. What is the velocity and frequency of sound?

Darya [45]

-- Speed = (distance) / (time to cover the distance) = 840/2.5 = 336 m/s

-- Frequency = (speed) / (wavelength) = 336/0.70 = 480 Hz.

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3 years ago

A 5-kg ball collides inelastically head-on with a 10-kg ball, which is initially stationary. Which of the following statements i

NARA [144]

Answer:

The magnitude of the change of velocity the 5-kg ball experiences is less than that of the 10-kg ball.

Explanation:

In inelastic collision, the total momentum is always conserved after collision but the kinetic energy is reduced.

Momentum is Mass X velocity.

5 kg ball is in motion, while 10 kg ball is stationary; that is zero velocity.

The momentum of 10 kg ball before collision is zero while the momentum of 5 kg ball before collision is more than zero. Therefore, the magnitude of change in momentum will not be equal.

Next possible options are in kinetic Energy

Initial Kinetic energy = $\frac{1}{2}mu^2$

Final kinetic energy = $\frac{1}{2}mv^2$

Change in kinetic energy = Final Kinetic Energy - Initial Kinetic Energy

Change in kinetic energy of 5kg ball = $\frac{1}{2}mv^2 -\frac{1}{2}mu^2 = \frac{1}{2}m(v-u)^2$

Since the 5-kg ball has initial velocity (u), the magnitude of the change in velocity will be reduced.

Change in kinetic energy of 10kg ball:

the ball is initially at rest, therefore the initial velocity (u) will be zero (0)

Δ K.E = $\frac{1}{2}mv^2 -\frac{1}{2}mu^2 = \frac{1}{2}m(v-u)^2 = \frac{1}{2}m(v-0)^2 = \frac{1}{2}mv^2$

From the solution above, the magnitude of the change in velocity experienced by 10 kg ball is higher than 5 kg ball.

Hence, The magnitude of the change of velocity the 5-kg ball experiences is less than that of the 10-kg ball

4 0

3 years ago

If a 60 kg woman, runs up a flight of stairs having a total rise of 4.0m in a time of 4.2s. What average power did she supply?

LenKa [72]

PE = m * g * h
PE = 60 * 9.8 * 4
PE = 2352 J

Power = E/t

Power = PE/t
Power = 2352/4.2
Power = 560 Watt

6 0

4 years ago