Answer:
In physics, a force is any interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull.
 
        
             
        
        
        
10cm per beat, it would take 3 beats to travel 30cm x
        
             
        
        
        
Answer:
a. k = (1/k₁ + 1/k₂)⁻¹ b. k = (1/k₁ + 1/k₂ + 1/k₃)⁻¹
Explanation:
Since only one force F acts, the force on spring with spring constant k₁ is F = k₁x₁ where x₁ is its extension
the force on spring with spring constant k₂ is F = k₂x₂ where x₁ is its extension 
Let F = kx be the force on the equivalent spring with spring constant k and extension x.
The total extension , x = x₁ + x₂
x = F/k = F/k₁ + F/k₂
1/k = 1/k₁ + 1/k₂
k = (1/k₁ + 1/k₂)⁻¹
B 
The force on spring with spring constant k₃ is F = k₃x₃ where x₃ is its extension
Let F = kx be the force on the equivalent spring with spring constant k and extension x.
The total extension , x = x₁ + x₂ + x₃
x = F/k = F/k₁ + F/k₂ + F/k₃
1/k = 1/k₁ + 1/k₂ + 1/k₃
k = (1/k₁ + 1/k₂ + 1/k₃)⁻¹
 
        
                    
             
        
        
        
Answer:
The energy stored is: 62.5 Joules
Explanation:
Given
 --- spring constant
 --- spring constant
 --- stretch
 --- stretch
Required
The amount of energy 
This is calculated as:




 
        
             
        
        
        
<span>6160 joules
    to lift 1 newton 1 metre requires 1 joule
 there are 10 newtons in one kilo
    so 77(kg) x 8 (metres) x 10 (newtons/kilo) = 6160 joules</span>