2 Forces and Particle Equilibrium Free Online FlashCards

What two properties define a force?

A force is a vector, so it has both magnitude and direction.

What is the SI unit of force?

The newton (N).

What does each feature of a force arrow represent?

Arrow length represents magnitude, orientation represents direction, and the line of action shows where the force acts.

How do you find a 2D force's magnitude from its components?

For a two-dimensional force, $F=\sqrt{F_x^2+F_y^2}$.

How do force components determine a 2D direction angle?

Use $\theta=\operatorname{atan2}(F_y,F_x)$, measured counterclockwise from the positive $x$-axis. The component signs identify the quadrant.

How do you resolve a force angled from the positive $x$-axis?

For an angle measured from the positive $x$-axis, $F_x=F\cos\theta$ and $F_y=F\sin\theta$.

What changes if the force angle is measured from the vertical?

The perpendicular component formulas switch roles; assign each component a sign based on its actual direction.

What does resolving a force into components mean?

It replaces the original force with perpendicular component vectors whose vector sum equals that force.

What makes a force system concurrent?

A force system is concurrent when all its forces' lines of action pass through one common point.

What should a particle's free-body diagram show?

A free-body diagram isolates the particle and shows every external force acting on it, such as applied forces, cable tensions, and weight.

How is the resultant force defined?

The resultant is the vector sum of all forces: $\mathbf R=\sum_i\mathbf F_i$.

What component equations express particle equilibrium?

The resultant force is zero. In two dimensions, $\sum F_x=0$ and $\sum F_y=0$; in three dimensions, also $\sum F_z=0$.