Question

George is trying to move a heavy bookshelf across the classroom. He pushes on the bookshelf with a force of 57 N to the right Friction is resisting his movement with a force of78 N. The bookshelf does not move. A friend comes to help George, The friend pushes the bookshelf in the same direction as George with a force of 25 N. What will happen tothe bookshelf?The bookshelf will not move,0000The bookshelf will move to the left with a force of 25 NThe bookshelf will move to the right with a force of 82 NThe bookshelf will move to the right with a force of 4 N.

Answer 1

Given data:

* The force applied on the bookshelf towards the direction of motion by George is,

`F_1=57\text{ N}`

* The force applied on the bookshelf towards the direction of motion by the friend of George is,

`F_2=25\text{ N}`

* The force of friction opposite to the direction of motion is,

`F=78\text{ N}`

Solution:

Thus, the net force acting on the bookshelf is,

`F_(net)=F_1+F_2-F`

Here, the negative sign before the friction force indicates the direction of friction force is oppoiste to the direction of motion,

Substituting the known values,

`\begin{gathered} F_(net)=57+25-78 \\ F_(net)=4\text{ N} \end{gathered}`

Here, the positive value of net force indicates the net force is acting in the direction of motion of the bookshelf.

Thus, the bookshelf will move to the right with a force of 4 N.

Hence, 4th option is the correct answer.