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