Question

Hey all,
Pls list important equations of cbse class 9
Chapter sound,
Work & energy.

Answer 1

 equation in chapter sound that is 
frequency = number of oscillations / time
            v = 1/t
relationship between speed(V) , frequency(v) and wave length 

wave velocity = distance covered/ time taken 
                     = wave length / time taken
                    v= wave length / t
as we know v = 1/t 
connecting V and wave length in terms of frequency (v) we can write as
wave velocity =  frequency * wave length

work and energy 
work done = force on the object * displacement of the object
w = f *s  
 
kinetic energy = 1/2 mv²
mass of the object = m 
speed of the object = v

potential energy = mgh 
m = mass of the body 
g= 9.8m/s²
h = height of the object from ground 

power = work/ time 
p = w /t