A block of wood of mass 55.0 g floats in a swimming pool, oscillating up and down in simple harmonic motion with a frequency of 3.00 Hz.
a) What is the value of the effective spring constant of the water?
b) A partially filled water bottle of almost the same size and shape as the block of wood but with mass 250. g is placed on the water’s surface. At what frequency will the bottle bob up and down?
THINK:
To find the spring constant, we have to relate the mass and frequency.
RESEARCH:
The angular frequency is given by
And frequency is 
SIMPLIFY:
The spring constant can be expressed as

The new frequency can be expressed as

CALCULATE:
(a) Spring constant can be calculated as

(b) Frequency of the bottle bob can be calculated as

ROUND:
The result should be rounded to three significant figures.
a) The spring constant 
b) The frequency is 