Physics

1.Supersonic plane fly with the speed

less than the speed of sound of sound greater than the speed of sound of light

2.Mach number is used in connection with the speed of

sound aircraft spacecraft ships

3.On a stationary sail boat, air is blown from a fan attached to the boat. The boat

moves in opposite direction in which the air is blown does not move moves in the same direction in which air blows spins around

4.Rainbow is due to

absorption of sunlight in minute water droplets diffusion of sunlight through water droplets ionisation of water deposits refraction and reflection of sunlight by water droplets

5.Stars which appear single to the naked eye but are double when seen through a telescope are

novas and supernovas binaries asteroids quasars