Explanation:
Write in scientific notation.
4000 = 4.0×10³
 
        
             
        
        
        
Answer: 815.51 m
Explanation:
This situation is related to projectile motion or parabolic motion, in which the initial velocity of the bullet has only y-component, since it was fired straight up. In addition, we are dealing with constant acceleration (due gravity), therefore the following equations will be useful to solve this problem:
 (1)
 (1)
 (2)
 (2)
Where:
 is the final velocity of the bullet
 is the final velocity of the bullet
 is the initial velocity of the bullet
 is the initial velocity of the bullet
 is the acceleration due gravity, always directed downwards
 is the acceleration due gravity, always directed downwards
 is the time
 is the time 
 is the vertical position of the bullet at
 is the vertical position of the bullet at 
Let's begin by finding  from (1):
 from (1):
 (3)
 (3)
 (4)
 (4)
Now we have to substitute (4) in (2):
 (5)
 (5)
Isolating  :
:
 This is the displacement  of the bullet after 6.9 s
 This is the displacement  of the bullet after 6.9 s
 
        
             
        
        
        
Answer:
The final speed of the stone as it lift the ground is 23.86 m/s.             
Explanation:
Given that,
Force acting on the rock, F = 3 N
Distance, d = 16 m
Initial speed of the stone, u = 22 m/s 
We need to find the rock's speed just as it left the ground. It can be calculated using work energy theorem as :

So, the final speed of the stone as it lift the ground is 23.86 m/s.                                                     
 
        
             
        
        
        
Answer: The normal of the plane must be parallel to the electric field vector.
Explanation:
the normal to the surface is defined as a versor that is perpendicular to the plane.
Now, if the angle between this normal and the line of the field is θ, we have that the flux can be written as:
Φ = E*A*cos(θ)
Where E is the field, A is the area and θ is the angle already defined.
Now, this maximizes when θ = 0.
This means that the normal of the surface must be parallel to the electric field