Question

A mule uses a rope to pull a box that weighs 145 N across a level surface with constant velocity. The rope makes an angle of 25.0° above the horizontal, and the tension in the rope is 85 N. What is the normal force of the floor on the box?a. 145 Nb. 109 Nc. 36 Nd. 77 N I just need the answer and no explanation

Answer 1

We are given the following information

Weight of box = 145 N

Angle above the horizontal surface = 25.0°

Tension in the rope = 85 N

Normal force = ?

Let us sketch a diagram to better understand the problem.

As you can see, the normal force is acting in the upward direction.

The weight of the box (mg) is acting in the downward direction.

The tension force applied to the box can be decomposed into two components,

The horizontal component of tension is parallel to the surface of the box.

`F_(wx)=85\cos 25\degree`

The vertical component of tension is perpendicular to the surface of the box.

`F_(wy)=85\sin 25\degree`

Since the force pulls the pox upward, the normal force will be less than the weight and is given by

`\begin{gathered} F_n=mg-F_(wy) \\ F_n=145-85\sin 25\degree \\ F_n=109\; N \end{gathered}`

Therefore, the normal force of the floor on the box is 109 N