The height need to change by 4 to double the final velocity.
<h3>Final velocity of the object</h3>
The final velocity of an object during a free fall is related to maximum height of fall as given the equation below.
v = √2gh
v² = 2gh
v²/h = 2g
v₁²/h₁ = v₂²/h₂
when v₂ = 2v₁, change in height is calculated as;
h₂ = h₁v₂²/v₁²
h₂ = (h₁ (2v₁)²) / (v₁)²
h₂ = 4h₁v₁² / v₁²
h₂ = 4h₁
Thus, the height need to change by 4 to double the final velocity.
Learn more about final velocity here: brainly.com/question/25905661
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Answer:
Explanation:
The angle between the polariser 1 and 2 is 60°
If I₁ be the intensity of light after polariser 1 , its intensity after polariser 2 that is I₂ can be expressed as follows 
I₂ = I₁ cos² 60
= I₁ x 1/4 
=  I₁ x 
 
        
             
        
        
        
When the ball goes upward, the velocity is decreasing. Therefore, the kinetic energy is decreased. The potential energy when the ball's height increases also increases. When the ball reaches maximum, the velocity becomes zero and the kinetic energy is minimum. 
        
                    
             
        
        
        
By Newtons Third law this is an action reaction pair of force
So the momentum is the same
30*20=50*x where x is velocity 
x= 12m/s
direction is towards left since they act in opposite directions
        
                    
             
        
        
        
Answer:
43.2 N
Explanation:
 = Wavelength = 0.75 m
 = Wavelength = 0.75 m
f = Frequency = 40 Hz
m = Mass of string = 0.12 kg
L = Length of string = 2.5 m
 = Linear density =
 = Linear density = 
Velocity of wave is given by

The tension in string is given by

The tension in the string is 43.2 N