Answer:
<em>Refraction is the change in direction of waves that occurs when waves travel from one medium to another. ... Diffraction is the bending of waves around obstacles and openings. The amount of diffraction increases with increasing wavelength.</em>
You change the independent variable.
Frequency = 1 / period
1 / 4sec = one fourth per sec = 0.25 Hz
Balance:
a book resting on a table
a car driving at 10 miles per hour in constant velocity
a cat sitting on a chair
a bulb that attach to the ceiling
your grandma sleeping on a bed
Unbalance:
your brother sprinting across the kitchen
a ball rolling at 5 m/s^2
your mom trying to run at 2 m/s^2 to spank you
you dropping your coffee mug on a floor
a cat jumping out of your bed
a tear from your eye falling through the floor
Hope this helps