Sound waves are created by which of the following:
a.) vibrations of particles in the air
b.) vibrations in your vocal cords
c.) vibrations of musical instruments
d.) all of the above

Sound waves are created by vibrations of particles in the air, through vocal cords, and musical instruments. i.e. all of the given options

Option D

Explanation:

There are three basic requirements to produce sound waves,

A source means something which can produce vibrations. The second thing is that there should be a medium like air, water or something else through which the vibrations may travel.

The third and the last thing is the receiver. Here all the options given in the question can be considered right as sound waves can be produced through the vibrations of air particles, vocal cords or musical instruments.

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

which piece of furniture will have the most inertia and give the furniture movers the most difficulty in moving?  

answer

a 75kg dining table