When were Earth’s landmasses first recognizable as the continents we know today? 10 million years ago 135 million years ago 180
2 answers:
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Explanation:
The given data is as follows.
mass, m = 75 g
Specific heat of water = 4.18
First, we will calculate the heat required for water is as follows.
q =
=
= 8464.5 J/mol
= 8.46 kJ ......... (1)
Also, it is given that = (20 + 273) K = 293 K and specific heat of ice is 2.108 kJ/kg K.
Now, we will calculate the heat of fusion as follows.
q =
=
= -46.32 kJ ......... (2)
Now, adding both equations (1) and (2) as follows.
8.46 kJ - 46.32 kJ
= -37.86 kJ
Therefore, we can conclude that energy in the form of heat (in kJ) required to change 75.0 g of liquid water at to ice at
is -37.86 kJ.
A. 90.1 m
The wavelength of a wave is given by:
where
v is the speed of the wave
f is its frequency
For the sound emitted by the whale, v = 1531 m/s and f = 17.0 Hz, so the wavelength is
B. 102 kHz
We can re-arrange the same equation used previously to solve for the frequency, f:
where for the dolphin:
v = 1531 m/s is the wave speed
is the wavelength
Substituting into the equation,
C. 13.6 m
Again, the wavelength is given by:
where
v = 340 m/s is the speed of sound in air
f = 25.0 Hz is the frequency of the whistle
Substituting into the equation,
D. 4.4-8.7 m
Using again the same formula, and using again the speed of sound in air (v=340 m/s), we have:
- Wavelength corresponding to the minimum frequency (f=39.0 Hz):
- Wavelength corresponding to the maximum frequency (f=78.0 Hz):
So the range of wavelength is 4.4-8.7 m.
E. 6.2 MHz
In order to have a sharp image, the wavelength of the ultrasound must be 1/4 of the size of the tumor, so
And since the speed of the sound wave is
v = 1550 m/s
The frequency will be