Answer:
dam/hydro power
Explanation:
estuary is the place where rivers meet the ocean, there are a lot of currents there (waves...) so it likely means thery use a dam or some sort of way of collecting electricity from the motion of the water there. many birds live in estuaries because of being able to find fish to feed from
 
        
             
        
        
        
Answer:
1/4 times your earth's weight
Explanation:
assuming the Mass of earth = M
Radius of earth = R
∴ the mass of the planet= 4M
the radius of the planet = 4R
gravitational force of earth is given as = 
where G is the gravitational constant
Gravitational force of the planet = 
                                                        =
                                                        =
recall, gravitational force of earth is given as = 
∴Gravitational force of planet = 1/4 times the gravitational force of the earth
you would weigh 1/4 times your earth's weight
 
        
             
        
        
        
Answer:
0.074m/s
Explanation:
We need the formula for conservation of momentum in a collision, this equation is given by,

Where,
 = mass of ball
 = mass of ball
 = mass of the person
 = mass of the person
 = Velocity of ball before collision
 = Velocity of ball before collision
 = Velocity of the person before collision
 = Velocity of the person before collision
 = velocity of ball afer collision
 = velocity of ball afer collision
 = velocity of the person after collision
= velocity of the person after collision
We know that after the collision, as the person as the ball have both the same velocity, then,


Re-arrenge to find  ,
,

Our values are,
 = 0.425kg
= 0.425kg
 = 12m/s
= 12m/s
 = 68.5kg
= 68.5kg
 = 0m/s
= 0m/s
Substituting,


<em />
<em>The speed of the person would be 0.074m/s after the collision between him/her and the ball</em>
 
        
             
        
        
        
(3) The frictional force exerted by the floor on the box