Answer:
B.useful products
Explanation:
industry is a sector that produces goods or services within an economy
Answer:
Increasing the mass and decreasing the distance between the two objects.
Explanation:
An increase in mass will cause them to have a stronger pull or gravity. A decrease of distance will make it easier for the objects to fall into each other because they would be further into the other objects area of influence.
Answer:
v = wavelength * frequency
frequency = 5200 m/s / .2 m = 26000 / sec
20,000 / sec is optimistic for the upper frequency of human hearing
So 26,000 is above the hearing range for human ears
Sound waves....................................