Answer:
It is very important because scientists, especially the ones with empirical experiments and results, are prone to error and the empirical data is in need to be under strict observation done not only by many scientists but also by expermiented ones. This guards everybody to change the parameters suddenly which can affect the real results of an experiment 
Explanation:
 
        
                    
             
        
        
        
(a) The stress in the post is 1,568,000 N/m²
(b) The strain in the post is  7.61 x 10⁻⁶  
(c) The change in the post’s length when the load is applied is 1.9 x 10⁻⁵ m.
<h3>Area of the steel post</h3>
A = πd²/4
where;
 d is the diameter
A = π(0.25²)/4 = 0.05 m²
<h3>Stress on the steel post</h3>
σ = F/A
σ = mg/A
where;
- m is mass supported by the steel
 - g is acceleration due to gravity
 - A is the area of the steel post
 
σ = (8000 x 9.8)/(0.05)
σ = 1,568,000 N/m²
<h3>Strain of the post</h3>
E = stress / strain
where;
- E is Young's modulus of steel = 206 Gpa
 
strain = stress/E
strain = (1,568,000) / (206 x 10⁹)
strain = 7.61 x 10⁻⁶
<h3>Change in length of the steel post</h3>
strain = ΔL/L
where;
- ΔL is change in length
 - L is original length
 
ΔL = 7.61 x 10⁻⁶ x 2.5
ΔL = 1.9 x 10⁻⁵ m
Learn more about Young's modulus of steel here: brainly.com/question/14772333
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Answer:2.6 h
Explanation:
Given
Total Trip distance=450 miles
Meeting starts after 10.8 hours 
safe Fastest speed is  55 mi/h
so if he drives all the to the meeting with max speed then it takes 
and total allowable time is 10.8 
Therefore longest time he can spend over dinner is 
 
        
             
        
        
        
Your answer would be motion because u need force to stop motion or anything at that matter