Answer:
1.31498 kg
0.72050 s
0.72050 s
Explanation:
m = Mass of block
g = Acceleration due to gravity = 9.81 m/s²
k = Spring constant = 100 N/M
x = Displacement = 0.129 m
The force balance is 

The mass of the block is 1.31498 kg
Time period is given by

The period of oscillations is 0.72050 s
The time period does not depend on the acceleration due to gravity. It varies with the mass and the spring constant.
Hence, the time period would be the same
 
        
             
        
        
        
Answer:
2.24 seconds 
Explanation:
xf = xo + vo t + 1/2 at^2 
45 = 0 + 15 t  + 1/2 (4.5) t^2 
    2.25 t^2 + 15t - 45 = 0              Quadratic formula shows  t = 2.24 seconds 
 
        
             
        
        
        
We use the work formula to solve for the unknown in the problem. The formula for work is expressed as the product of the net force and the distance traveled by the object. We were given both the force and the distance so we can solve work directly.
Work = 250 N x 50 m = 12500 J
Thus, the answer is C.