I think it's a) 1st Newton's law... so sorry if it's wrong...
Answer: D(t) = 
Explanation: A harmonic motion of a spring can be modeled by a sinusoidal function, which, in general, is of the form:
y =
or y = 
where:
|a| is initil displacement
is period
For a Damped Harmonic Motion, i.e., when the spring doesn't bounce up and down forever, equations for displacement is:
or 
For this question in particular, initial displacement is maximum at 8cm, so it is used the cosine function:
period =
12 =
ω = 
Replacing values:

The equation of displacement, D(t), of a spring with damping factor is
.
Answer:
49 N
Explanation:
In order to move the box at constant speed, the acceleration of the box must be zero (a=0): this means, according to Newton's second law,
F = ma
that the net force acting on the box, F, must be zero as well.
Here there are two forces acting on the box in the horizontal direction while it is moving:
- The force of push applied by the guy, F
- The frictional force, 
For an object moving on a flat surface, the frictional force is given by

where
is the coefficient of friction
m is the mass of the box
g is the acceleration of gravity
So the equation of the forces becomes

And substituting:

We find the force that must be applied by the guy:

Answer:
0.3cm
Explanation:
Y = 0.3 sin(0.5x - 50t) compare with,
y = A sin(kx - wt)
A = 0.3m
Answer:
1st t=d/s
2nd s=d/t
5th d=st
are all of the variations I came up with
Explanation:
the original formula for speed is s=d/t
then, I created a ratio of s/1=d/t and cross multiplied to find d=st
then, I isolated the t in one side by dividing by s on both sides.