Acrate of books is to be put on a truck with the of some planks sloping up at 36◦ . the mass of the crate is 80 kg, and the coefficient of sliding friction between it and the planks is 0.8. you and your friends push horizontally with a force f~ . the acceleration of gravity is 9.81 m/s 2 .

F= 2.86KN

Explanation:

The attached diagram shows the motion of crate on a single line The forces acting on it have been resolved as shown in the attached figure.The kinetic friction opposes the motion.Now crate is moving with constant speed so the acceleration is constant.

Applying Newton's second law to determine the force F and also substituting the values for to eliminate normal force

F = ma

Now  and   components are zero

Horizontal and vertical forces are Force on crate, weight of crate and kinetic friction

therefore

 >>>  (1)

By putting the above equation in equation 1 we get F

By putting values we get

F =

F= 2860.8 N

F= 2.86KN

and 1and 1

the box does not move because you need to use a force greater than 300 n. you are only using 50 n. it needs to at least be 301 n for the box to move because then it is an unbalanced force and it will move the way that the greater force is pushing it. if you use only 300 n it will be a balanced force and will not move because the force you are exerting on the   box is the same as its force.

hope this !

im sorry if i went too in depth, i am going to include a link to a video on khan academy that will explain this.   hope that you like the video and that it explains more in detail to you.

that is the link.