I don't see any units of measurement or speed I don't see anything
Explanation:
(a) Net force acting on the block is as follows.

or, ma = -mg Sin (\theta)[/tex]
a = 
= 
= -3.35 
According to the kinematic equation of motion,

Distance traveled by the block before stopping is as follows.
s = 
= 
= 21.5 m
According to the kinematic equation of motion,
v =
0 = 
= 7.16 sec
Therefore, before coming to rest the surface of the plane will slide the box till 7.16 sec.
(b) When the block is moving down the inline then net force acting on the block is as follows.

ma = 
a = 
= 
= 3.35 
Kinematics equation of the motion is as follows.
s = 
21.5 m = 
= 
= 3.58 sec
Hence, total time taken by the block to return to its starting position is as follows.
t = 
= 7.16 sec + 3.58 sec
= 10.7 sec
Thus, we can conclude that 10.7 sec time it take to return to its starting position.
The amount of solid does not affect how you are describing the solid so a is the answer
Answer:
v=39.05 m/s
Explanation:
Given that
x= 56 cm
F= 158 N
m= 58 g = 0.058 kg
Lets take spring constant = k
At the initial position,before releasing the arrow
F= k x
By putting the values
F= k x
158= 0.56 k
k=282.14 N/m
Now from energy conservation
Lets take final speed of the arrow after releasing

k x²=mv²
282.14 x 0.56² = 0.058 v²
v=39.05 m/s