How does the sound produced by a vibrating object in a medium reach your ear?

How does the gravitational force between two objects depend upon the.distance between them?

Explain how sound is prodeuced by your school bell.

When a sound is reflected from a distant object, an echo is produced. Let the distance between the reflecting surface and the source of sound production remains the same. Do you hear echo sound on a hotter day?

How does the gravitational force between two objects depend upon their masses?

A bolt of mass 0.3 kg falls from the ceiling of an elevator moving down with an uniform speed of 7 m s^-1 . It hits the floor of the elevator (length of the elevator = 3 m) and does not- rebound. What is the heat produced by the impact? Would your answer be different if the elevator were stationary?

How does the velocity of sound depend upon pressure and temperature of the medium.

One-half of a convex lens is covered with a black paper. Will this lens produce a complete image of the object? Verify your answer experimentally. Explain your observations.