Instructions

1- Place the elastic cord in position (2,2)

2- Draw the force which you think would balance the previous one.  Use the arrow keys on the keyboard.  Find out if your answer is correct clicking on "play".

3- Click on home and choose two forces with the control.  Put them where you like and calculate the resultant force. 

4- Click on home and do the same but with three forces acting on the object.

You have just calculated the resultant force of up to three forces.  The process for the case where there are more forces follows the same logic.

Learn:

The force capable of countering the effect produced by the resultant force is called the counterbalance.  It is a force with the same module, the same orientation but the opposite direction compared with the resultant.  The components of the counterbalance are therefore equal to those of the resultant but with the opposite sign, (-Fx,-Fy).

An object is in translational equilibrium when it has a constant velocity. (velocity =0 m/s, that is stopped, which is a constant velocity!)

Work with the visual above

1. Draw two elastic forces: Fa=(-1.00 N,1,00 N) and Fb=(1.15 N,0.45 N)

2. Calculate the resultant in your notebook. Check it with the visual

3. Calculate the force which balances Fa and Fb. Check it with the visual

4.. Draw three elastic forces: Fa=(-1.75 N, 0.60 N), Fb=(1.45 N , 0.00 N), Fc=(-1.50 N , -1.00 N)

5. Calculate the resultant and the counterbalance in your notebook.  Check it with the visual