Answer:
0.34 sec 
Explanation:
Low point of spring ( length of stretched spring ) = 5.8 cm
midpoint of spring = 5.8 / 2 = 2.9 cm
Determine the oscillation period 
at equilibrum condition 
Kx = Mg 
g= 9.8 m/s^2
x = 2.9 * 10^-2 m
k / m = 9.8 / ( 2.9 * 10^-2 ) =  337.93
note : w =  =
   =  = 18.38 rad/sec
 = 18.38 rad/sec
Period of oscillation =  
                                   = 0.34 sec
 
        
             
        
        
        
Dispersion occurs due to the different degrees of refraction experienced by different colours of light. Light of different colours may travel with the same speed in a vacuum, but they travel at different speeds in some refracting medium. The speed of violet light is relatively lower than that of red light.