I will be so thankful if u answer correctly!!​

(a) 10N

The sketch of the two cases has been attached to this response.

Case 1: The box is pushed by a horizontal force F making it to move with constant velocity.

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;

∑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]

Substitute these values into equation (i) as follows;

F -   = m x a

F -   = 50 x 0

F -   = 0

F =              -------------------(ii)

Case 2: The box is pushed by a horizontal force 1.5F making it to move with a constant velocity of 0.1m/s²

In this case, the same frictional force is opposing the movement of the box.

∑F = 1.5F -  

m = 50kg

a =  0.1m/s²

Substitute these values into equation (i) as follows;

1.5F -   = m x a

1.5F -   = 50 x 0.1

1.5F -   = 5            ---------------------(iii)

Substitute = F from equation (ii) into equation (iii) as follows;

1.5F - F = 5            

0.5F = 5            

F = 5 / 0.5

F = 10N

Therefore, the value of F is 10N

coil wire, increase current, put iron inside the coil