Me with the formular of this question and the solvings.

Explanation:

Net Force

The second Newton's law explains how to understand the dynamics of a system where several forces are acting. The forces are vectorial magnitudes which means the x and y coordinates must be treated separately. For each component, the net force must equal the mass by the acceleration, i.e.

The box with mass m=20 kg is pulled by a rope with a angle above the horizontal. It means that force (called T) has two components:

We'll assume the positive directions are to the right and upwards and that the box is being pulled to the right. There are two forces in the x-axis: The x-component of T (to the right) and the friction force (to the left). So the equilibrium equation for x is

There are three forces acting in the y-axis: The component of T (upwards), the weight (downwards), and the Normal (upwards). Since there is no movement in the y-axis, the net force is zero and:

Rearranging:

Solving for N in the y-axis:

The friction force is given by

Replacing in the equation for the x-axis, we have

Replacing the formula for N in the equation for the x-axis  

Operating and rearranging

Solving for T:

Plugging in the given values:

at right angles to each other