Answer:
A. The wavelengths of the new sound waves are longer
Explanation:
This is the Doppler effect which can be best illustraded for the case of a siren of an ambulance approaching us having a greater frequency and getting lower in frequency and deeper as the ambulance passes us.
Since the wavelength is inversely proportional to the frequency it follows the wavelengths are longer when the frequency decreases lowering its pitch and getting deeper.
A baseball would hit the bat harder. This is because the baseball is a lot heavier and more dense than the plastic ball. The keyword that you're looking for is density. The baseball is dense.
Answer:
Explanation:
the variations in riser height or tread depth should not be grater than that is equal to 9.5 mm but the maximum riser height should be the 
but variation in riser height should not exceed to . The minimum riser height should be 7 inches which is equal to the 178 mm
Answer:
The answer is D. A Vacumn
Explanation:
Sound cannot travel through a vacuum. A vacuum is an area without any air, like space. So sound cannot travel through space because there is no matter for the vibrations to work in.
Answer:
Explanation:
Given
object of mass m is suspended from spring and set in oscillation with time Period T
We know Time period of a mass in oscillation is given by
where k=spring constant
When mass m is replaced by a mass of 2 m time period is given by
i.e. New time period becomes 
times of previous one
