1.1 System of Coplanar Forces:
Concurrent Forces:
Parallel Forces:
Non-concurrent Non-parallel Forces:
The effect of a force on a rigid body is the same whether the force is applied at its original point or along its line of action.
\( \mathbf{F} = \mathbf{F}_1 + \mathbf{F}_2 + \ldots + \mathbf{F}_n \)
\( \mathbf{F}_x = \sum \mathbf{F}_i \cos \theta_i \)
\( \mathbf{F}_y = \sum \mathbf{F}_i \sin \theta_i \)
Concurrent Forces: \( \mathbf{R} = \sum \mathbf{F}_i \)
Parallel Forces: \( R = \sum F_i \)
Non-concurrent Non-parallel Forces: \( \mathbf{R} = \sqrt{\left(\sum F_x\right)^2 + \left(\sum F_y\right)^2} \)
\( \mathbf{M} = \mathbf{r} \times \mathbf{F} \)
Couples: \( \mathbf{M} = \mathbf{F} \cdot d \)
Varignon's Theorem: \( \mathbf{R} = \sqrt{\mathbf{F}_1^2 + \mathbf{F}_2^2} \)
For distributed loads, integrate to find resultant forces and moments.
\( Q_x = \int_A x \, dA \)
\( Q_y = \int_A y \, dA \)
\( \bar{x} = \frac{Q_x}{A} \)
\( \bar{y} = \frac{Q_y}{A} \)
Concurrent Forces: \(\sum \mathbf{F} = 0\) and \(\sum \mathbf{M} = 0\) (Net force and net moment are zero)
Parallel Forces: \(\sum F = 0\) and \(\sum M = 0\) (Net force and net moment are zero)
Non-concurrent Non-parallel Forces: \(\sum \mathbf{F} = 0\) and \(\sum \mathbf{M} = 0\) (Net force and net moment are zero)
Couples: \(\sum \mathbf{M} = 0\) (Net moment is zero)
Free Body Diagrams:
Simple Beams: Supported at both ends
Compound Beams: Combinations of simple beams
Supports:
Reactions:
For various types of loads on beams, use the equations:
<!DOCTYPE html> Friction and Kinematics Formulas
Force of static friction (\(F_{\text{static}}\)):
\[ F_{\text{static}} \leq \mu_s \cdot N \]
Force of kinetic friction (\(F_{\text{kinetic}}\)):
\[ F_{\text{kinetic}} = \mu_k \cdot N \]
Static friction coefficient (\(\mu_s\))
Kinetic friction coefficient (\(\mu_k\))
Angle of friction (\(\theta\)):
\[ \tan \theta = \frac{{\text{Opposite side}}}{{\text{Adjacent side}}} = \frac{{\mu_s}}{{1}} \]
The cone of friction represents all possible directions of the frictional force.
Forces along the inclined plane:
\[ F_{\text{parallel}} = W \cdot \sin \theta \] \[ F_{\text{perpendicular}} = W \cdot \cos \theta \]
Equations for equilibrium:
\[ \sum F_x = 0 \] \[ \sum F_y = 0 \] \[ \sum M = 0 \]
Application to problems involving wedges and ladders.
Acceleration (\(a\)) as a function of time:
\[ a = \frac{dv}{dt} \]
Components of acceleration:
\[ a_t = \frac{dv}{dt} \] \[ a_n = \frac{v^2}{r} \]
Tangential component (\(a_t\)) and normal component (\(a_n\)) of acceleration.
Acceleration-time (\(a-t\), velocity-time (\(v-t\), and displacement-time (\(s-t\) curves.
Related numerical formulas.
The effect of a force on a rigid body is the same whether the force is applied at its original point or along its line of action.
\(\mathbf{F} = \mathbf{F}_1 + \mathbf{F}_2 + \ldots + \mathbf{F}_n\)
\(\mathbf{F}_x = \sum \mathbf{F}_i \cos \theta_i\)
\(\mathbf{F}_y = \sum \mathbf{F}_i \sin \theta_i\)
Concurrent Forces: \(\mathbf{R} = \sum \mathbf{F}_i\)
Parallel Forces: \(R = \sum F_i\)
Non-concurrent Non-parallel Forces: \(\mathbf{R} = \sqrt{\left(\sum F_x\right)^2 + \left(\sum F_y\right)^2}\)
\(\mathbf{M} = \mathbf{r} \times \mathbf{F}\)
Couples: \(\mathbf{M} = \mathbf{F} \cdot d\)
Varignon's Theorem: \(\mathbf{R} = \sqrt{\mathbf{F}_1^2 + \mathbf{F}_2^2}\)
For distributed loads, integrate to find resultant forces and moments.
\(Q_x = \int_A x \, dA\)
\(Q_y = \int_A y \, dA\)
\(\bar{x} = \frac{Q_x}{A}\)
\(\bar{y} = \frac{Q_y}{A}\)
Concurrent Forces: \(\sum \mathbf{F} = 0\) and \(\sum \mathbf{M} = 0\)
Parallel Forces: \(\sum F = 0\) and \(\sum M = 0\)
Non-concurrent Non-parallel Forces: \(\sum \mathbf{F} = 0\) and \(\sum \mathbf{M} = 0\)
Couples: \(\sum \mathbf{M} = 0\)
Free Body Diagrams:
Simple Beams: Supported at both ends
Compound Beams: Combinations of simple beams
Supports:
Reactions:
For various types of loads on beams, use the equations: