Frequency of a wave = 
                 (speed of the wave) divided by (wavelength)
or
                 (1) divided by (period of the wave) .
Period of the wave = 
                   (wavelength) divided by (speed of the wave)
or
                   (1) divided by (frequency of the wave) .
        
             
        
        
        
Answer:
Equilibrium
Explanation:
An object is in equilibrium when the vector sum of the force acting on the object is equal to zero. 
A body in equilibrium is at state of rest of rest or in motion with no external force acting on it. 
- The resultant of all forces acting on the body is zero. 
- In this case there is no net force and the body will be at rest.