D. It’s a composite because it’s a mixture of cement, sand, and other granular pieces.
.Answer:
The value of the work done is .
Explanation:
When a charged particle having charge is moving through an electric field , the net force () on the charge is
and the work done () by the particle is
Given, .
Substitute the value of electric field in equation (1) and then substitute the result in equation (2).
Answer:The speed of sound is greater in water than in air.
Explanation: The speed of a sound wave in a medium depends upon the density of the medium through which the sound is traveling. We know speed of a mechanical wave can be calculated as Frequency* Wavelength . Frequency does not change with the change of medium. It depends on the source frequency. But wavelength can be altered. As speed of sound is greater in water than in air and frequency remains the same, so wavelength should be increased to compensate the increase in speed of sound wave.
Boundary separating two masses of air of different densities