Answer:mechanical waves.
Explanation:
Mechanical waves require the particles of the medium to vibrate in order for energy to be transferred. For example, water waves, earthquake/seismic waves, sound waves, and the waves that travel down a rope or spring are also mechanical waves.
A motor is built to use all those things and produce mechanical energy.
Answer:
a An increase in the speed will lower the internal pressure
Explanation:
Bernoulli's fluid formula

where
P = Pressure
ρ = Density of fluid
g = Acceleration due to gravity
h = Height
v = Velocity of fluid
If there is no change in height then we get

According to the Bernoulli's principle when the speed of the fluid is larger in a region of streamline flow the pressure is smaller in that region. From the above equation it can be seen that increase in speed should simultaneously reduce pressure in order for their sum to be constant.
Answer:
The correct option is (B).
Explanation:
The Kepler's third law of motion gives the relationship between the orbital time period and the distance from the semi major axis such that,

It is mentioned that, an asteroid with an orbital period of 8 years. So,

So, an asteroid with an orbital period of 8 years lies at an average distance from the Sun equal to 4 astronomical units.