Answer:
The slope of a position-time graph can be calculated as:

where
is the increment in the y-variable
is the increment in the x-variable
We can verify that the slope of this graph is actually equal to the velocity. In fact:
corresponds to the change in position, so it is the displacement, 
corresponds to the change in time
, so the time interval
Therefore the slope of the graph is equal to

which corresponds to the definition of velocity.
Answer:
the penny will sink because it is more compressed and has less air bubbles and a stronger mass and the cork will do the exact opposite since it has less mass and more air pockets.
Explanation:
Hi there!
The period is given by:

T = Period (sec)
w = angular frequency (rad/sec)
According to the equation for SHM in terms of position:
y(t) = Asin(ωt + φ)
A = Amplitude (m)
ω = angular frequency (rad/sec)
t = time (sec)
φ = phase angle
In this instance, the angular frequency is given as 18π.
Plug this value into the equation for T:

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