STE - Static Equilibrium

Static Equilibrium

Static equilibrium involves objects that have no linear or angular velocity. By applying the conditions for translational and rotational equilibrium, we can solve for unknown force values. Translational equilibrium means that the sum of the forces is equal to zero. Rotational equilibrium means that the sum of the torques is equal to zero. To solve these problems it is necessary to draw a free body diagram showing the location of forces and the magnitude and direction of these forces. Please watch the following presentation that will discuss Static Equilibrium.

Static Equilibrium Practice

We will now practice solving problems using the concepts you learned in the presentation. Make sure that you show all your work when you solve your problems. The presentation will give you time to work through the problems, find a solution, and check your work. 

*Correction for the video below: In Problem 2 the question should be "A sign is hung from a 25kg pole" NOT "A sign is hung from a 20kg pole."

Static Equilibrium Self-Assessment

Now it is your turn. Complete the self-assessment questions to verify that you can apply the concepts of Static Equilibrium.

  1. A picture frame is 80 cm wide and 60 cm tall.   It has a mass of 5 kg and is hung by a nail that is off center.  The nail is 35 cm in from the left of the frame, and 5 cm from the top.  A man holds his finger so that it applies a horizontal force on the left of the frame to keep the frame level.

Problem 1 Image

    1. What is the magnitude of the force with which the man pushes against the frame?
    2. What is the magnitude and direction of the force of the nail?

SOLUTIONS Links to an external site.

  1. A window washer stands on a 5.00 m long board that has ropes tied 1.00 m from each end.  The board has a mass of 10 kg and the window washer has a mass of 75 kg.  He starts out in the middle of the board. How far can he travel to each end without the board tipping over? (assume that the board is horizontal, and that the ropes pull straight up at each end).

Problem 2 Image

SOLUTION Links to an external site.

  1. A 6m long ladder is placed against a wall so that it makes an angle of 40o to the horizontal.  The coefficient of friction between the floor and the ladder is 0.35, and the friction between the wall and the ladder is negligible.  The ladder has a mass of 15 kg.  A 65 kg man decides to climb the ladder. How far can he get up the ladder before it starts to slide? 

Problem 3 Image

SOLUTION Links to an external site.

Static Equilibrium Practice Problems

Download Static Equilibrium Practice Problems Links to an external site. for more practice. 

Download solutions Links to an external site. to the practice problems. 

VIDEOS CREATED BY GAVS

IMAGES SOURCED FROM PUBLIC DOMAIN