# Average Force

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

Average force, abbrevated as $$\bar F$$ or $$F_a$$, is used when the instantaneous velocity is not measured precisely between two points.  It uses the starting velocity, final velocity and the object's mass to determine the average force.  The equation and calculator for determining the average force is below.  If there is no change in velocity, the object may be in static equilibrium.

## Average Force formula

$$\large{ \bar F = m \; \frac { v_f \;-\; v_i } {t} }$$

$$\large{ \bar F = m \; \frac { \Delta v } {t} }$$

Symbol English Metric
$$\large{ \bar F }$$ = average force $$\large{ lbf }$$ $$\large{N}$$
$$\large{ m }$$ = mass $$\large{ lbm }$$ $$\large{ kg }$$
$$\large{ t }$$ = time $$\large{ sec }$$ $$\large{ s }$$
$$\large{ v_f }$$ = final velocity $$\large{\frac{ft}{sec}}$$   $$\large{\frac{m}{s}}$$
$$\large{ v_i }$$ = initial velocity $$\large{\frac{ft}{sec}}$$   $$\large{\frac{m}{s}}$$
$$\large{ \Delta v }$$ = velocity differential $$\large{\frac{ft}{sec}}$$   $$\large{\frac{m}{s}}$$