Because the average of one measurement would yield to itself, which provides nothing new to us. We need at least two for average to be purposeful.
        
                    
             
        
        
        
<h3>Answer: 500 Kilometers</h3>
Explanation:
The formula for finding distance is: speed × time
We must multiply:
200Km/h × 2.5 hours
This gives you 500 Km. 
<u>Remember: the formula to work out the distance -  speed x time.</u>
If the train speed is 200 km/h, it travels 200 km/h.
Now, we must multiply 200 by 2.5:
200 x 2.5 = 500
Our answer is 500 Kilometers.
 
        
        
        
Answer:
18.33 Ns
Explanation:
As the pitch back speed has the opposite direction as before, the change in velocity would be

So the change in momentum of the ball would be the product of its velocity change and its mass

This is equals to the impulse acted on the ball by the bat, which is 18.33 Ns
 
        
             
        
        
        
So Hooke's law says that that law is proportional to how much I stretch the spring. Alright. So f=kx<span>. x is the length of the spring now minus its length when it's relaxed and nobody's pulling on it. k is a constant called the spring constant.</span>
        
                    
             
        
        
        
Answer:
2 m = E / c^2      where m is mass of electron
E = h v     where v is the frequency ( nu) of the incident photon
E = h c / y      where y is the incident wavelength (lambda)
2 m = h / (c y)
y = h / (2 m c)      wavelength required
y = 6.62 * 10E-34 / (2 * 9.1 * 10E-31 * 3 * 10E8)  m
y = 3.31 / 27.3 E-11 m
y = 1.21 E -12 m   = .0121 Angstrom units