Answer:
The net force = 0 
Explanation:
The given information includes;
The mass of the crate = 250 kg
The way the helicopter lifts the crate = Uniformly (constant rate (speed), no acceleration)
In order to pull the crate upwards, the helicopter has to provide a force equivalent to the weight of the crate keeping the helicopter on the ground.
The weight of the crate = The mass of the crate × The acceleration due gravity acting on the crate
The weight of the crate,  ↓ = 250 kg × 9.81 m/s² = 2,452.5 N
↓ = 250 kg × 9.81 m/s² = 2,452.5 N
The force the helicopter should provide to just lift the crate,  ↑ = The weight of the crate = 2,452.5 N
↑ = The weight of the crate = 2,452.5 N
The net force,  =
 =  ↑ -
↑ -  ↓ = 2,452.5 N - 2,452.5 N = 0
↓ = 2,452.5 N - 2,452.5 N = 0
The net force = 0.
 
        
             
        
        
        
I think they can use more durable materials.
        
             
        
        
        
<h2>
Answer:</h2>
(a) 10N
<h2>
Explanation:</h2>
The sketch of the two cases has been attached to this response. 
<em>Case 1: The box is pushed by a horizontal force F making it to move with constant velocity.</em>
In this case, a frictional force  is opposing the movement of the box. As shown in the diagram, it can be deduced from Newton's law of motion that;
 is opposing the movement of the box. As shown in the diagram, it can be deduced from Newton's law of motion that;
∑F = ma    -------------------(i)
Where;
∑F = effective force acting on the object (box)
m = mass of the object
a = acceleration of the object
∑F = F -  
m = 50kg
a = 0   [At constant velocity, acceleration is zero]
<em>Substitute these values into equation (i) as follows;</em>
F -   = m x a
 = m x a
F -   = 50 x 0
 = 50 x 0
F -   = 0
 = 0
F =   -------------------(ii)
            -------------------(ii)
<em>Case 2: The box is pushed by a horizontal force 1.5F making it to move with a constant velocity of 0.1m/s²</em>
In this case, the same frictional force  is opposing the movement of the box.
 is opposing the movement of the box.
∑F = 1.5F -  
m = 50kg
a =  0.1m/s²
<em>Substitute these values into equation (i) as follows;</em>
1.5F -   = m x a
 = m x a
1.5F -   = 50 x 0.1
 = 50 x 0.1
1.5F -   = 5            ---------------------(iii)
 = 5            ---------------------(iii)
<em>Substitute </em> <em> = F from equation (ii) into equation (iii) as follows;</em>
<em> = F from equation (ii) into equation (iii) as follows;</em>
1.5F - F = 5            
0.5F = 5            
F = 5 / 0.5
F = 10N
Therefore, the value of F is 10N
<em />
 
        
        
        
Answer:
It is formed by a horizontal number line, called the x-axis, and a vertical number line, called the y-axis. 
Explanation: