Question

Flash and thunder are produced simultaneously . but thunder id heard a few second after is seen,why how does the speed of sound in air vary with rise in density of the medium? <br /><br />
give one ex. Where kinetic energy is transferred from one object to others. <br /><br /><br />
Archimedes could find the purity of king's crown using buoyancy. How?<br /><br /><br /><br /><br />
How do u define mechanical work ?<br />
Name and define SI unit of work.<br />
What do you mean positive and negative work ? Give example <br /><br />examples where work is zero

Answer 1

in the case of thunder and flash , the thunder is heard after few secs bcoz the speed of light is much faster than speed of sound and sound needs a medium to travel and if the density of a substance increase the sound travels faster and faster bcoz if the density increases the molecules get closer and as the molecule get closer the vibration is much faster and if vibration is faster it means speed of sound is increases