Forces in Equilibrium - Practice Problems

 

 

For each problem:

 

1.    Draw a freebody diagram.

2.    Draw in the x- and y- axes.

3.    Resolve each vector not already on the x- or y-axis into its x- and y- components.

4.    Write an equation for the sum of forces in the x- and y-direction. If the system is at rest or constant velocity, the net force is zero.

5.    Put your givens into the equations and solve for the unknowns.

 

 

        A 10.0 kg mass hangs from two strings, each making an angle of 35.0 with the ceiling.  What is the tension in each string? Solution

 

        A 15.0 kg block is at rest on a 40.0 incline.  Find the magnitude of the normal force and the friction. Solution

 

        A 25.0 kg wagon and rider is being pulled at constant velocity with a force of 50.0 N directed along the handle.  The handle makes an angle of 65.0 with the horizontal.  Find the magnitude of the normal force and the force of friction. Solution

 

        A 20.0 kg lawn mower is being pushed at constant velocity with a force of 65.0 N directed along the handle.  The handle makes an angle of 60.0 with the horizontal.  Find the magnitude of the normal force and the force of friction. Solution

 

        Honors problem: Find the tensions in strings 1 and 2 supporting a 20.0 N rock hanging from the ceiling. Strings 1 and 2 make angles of 30.0 and 40.0 with the ceiling, respectively. Solution