a. A dam is usually built at the site of hydroelectric power. As water accumulates, its potential power for producing electric power increases. As this water moves downstream from the dam, mostly through a fall, its kinetic energy is harnessed by turbines and converted to electric energy.
b. One factor is the height of the fall of the water from the dam. The higher the height the higher the kinetic energy of the water and hence can be converted to higher electric energy. The higher the number of coils of the turbine generator being rotated by the water, the higher the conversion to electric current.
c. One is impoundment. This type is the most common and involves the building of a dam to store water and later the water is released to turn turbines. The second type is diversion. This type does not require a dam. Some water is diverted from the main river to create a pen-stock that runs a turbine.
d. The advantage of hydroelectric power is that is is a clean energy source hence does not cause global warming. Global warming can have economic consequences. The operating cost of this type of plant is low hence the costs of electricity are able to be kept low for the consumers. 2 disadvantage is that creating a dam upstream causes a change in the physical and chemical characteristics of the river or water bodies affecting ecosystems. Another is that electricity is dependent on the water regime hence dependency is tied to climate.
Answer:
Cools ; size
Explanation:
The rate at which magma cools determines the size of the crystals in the new rock. Igneous rocks are formed from the cooling and solidification of molten magma which finds its way to the surface or depth of very low pressure beneath the surface. This place or depth of cooling of magma affects the cooling rate and hence the size of the crystals formed. Igneous rocks formed at depths below the surface have more time to cool and allows more time for Crystal growth and hence produce coarse grained crystal grains called Intrusive igneous rocks which have significantly larger crystals than those formed on the surface which cools rapidly and allowing very little time for crystal growth giving rise to the formation of fine grained crystals and are called extrusive igneous rocks.
Answer:

☯ Question :
- How fast is a wave travelling if it has a wavelength of 7 meters and a frequency of 11 Hz?
☯ 
☥ Given :
- Wavelength ( λ ) = 7 meters
- Frequency ( f ) = 11 Hz
☥ To find :
☄ We know ,

where ,
- v = speed of sound
- f = frequency
- λ = wavelength
Now, substitute the values and solve for v.
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✑ Additional Info :
- Frequency : The number of complete vibrations made by a particle of a body in one second is called it's frequency. It is denoted by the letter f . The SI unit of frequency is hertz ( Hz ).
- Wavelength : The distance between two consecutive compressions or rarefactions of a sound wave is called wavelength of that wave. It is denoted by λ ( lambda ) and it's SI unit is m.
- Speed of a sound wave : The distance covered by a sound wave in one second is called speed of sound wave. It depends on the product of wavelength and frequency of the wave.
Hope I helped!
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Answer:
C
Explanation:
The change in momentum of x has to be the opposite of the change in momentum of Y because the momentum is just transferred from one to another. But I'm still trying to figure it out how to calculate.