Power = 1800W (or 1.8KW by dividing by 1000)
Time = 3 hours 
Power = energy/ time
1.8KW = energy/ 3
x3
5.4Kw/h= energy 
(5.4KJ or 5400J used) 
$0.15 Kw/h
$0.15 X 5.4 = 0.81
Thus, cost $0.81
Hope this helps! 
 
        
             
        
        
        
Answer:
(a) The force between them quadruples
Explanation:
According to coulomb's law, initial force between the two charged objects is given as;

where;
k is coulomb's constant
q₁ is the charge on the first object
q₂ is the charge on the second object
r is the distance between the two objects
When the charges on both objects are doubled, then;
q₁ = 2q₁
q₂ = 2q₂
Force between the two charged objects will become
 
Therefore, the force between them quadruples
 
        
             
        
        
        
Answer:
Maximum height reached by the ball is 32 meters.
Explanation:
It is given that,
If a baseball is project upwards from the ground level with an initial velocity of 32 feet per second, then it's height is a function of time. The equation is given as :
 ...........(1)
...........(1)
t is the time taken
s is the height attained as a function of time.
Maximum height achieved can be calculated as :


-16 t + 32 = 0
t = 2 seconds
Put the value of t in equation (1) as :

s = 32 meters
So, the maximum height reached by the ball is 32 meters. Hence, this is the required solution.
 
        
             
        
        
        
Work = force x distance 
F= 2.5
D= 3
Work = 2.5 x 3 =7.5
Work = 7.5 J
J=Jules (Jules is the unit uses to calculate work)
        
             
        
        
        
A textbook would hit the ground first
Factors:
-Textbook weighs most
-Pillow is flat and fluffy not very aerodynamic) also is very light
-Paper airplane will glide to the ground do to its wings and will hit the ground last