Average Acceleration Formula

Acceleration is the rate of change for velocity, that is, change in velocity over a specified period of time. Average acceleration is the final velocity minus the initial velocity per time taken.

A_avg = Δv / Δt

A_avg = Average acceleration, m/s²

Δv = v_f - v_i, m/s

Δt = t_f - t_i, s

Average Acceleration Formula Questions:

1) Your friend's new car can go from 0 to 60 m/s in 7 sec. What is the acceleration?

Answer: The final velocity, v_f = 60 m/s; the initial velocity, v_i = 0; the final time, t_f = 7 sec; and the initial time, t_i = 0.

A_avg = Δv / Δt

A_avg = (60 m/s) / 7 s

A_avg = 12.86 m/s2

2) When driving along a side-road at 45 m/s, you see a child run out into the street, and rapidly slow to 3 m/s, within 1.5 sec. What is your acceleration?

Answer: The final velocity, v_f = 3 m/s; the initial velocity, v_i = 45 m/s; and the time, t = 1.5 sec.

A_avg = Δv / Δt

A_avg = (3 m/s - 45 m/s) / 1.5 sec

A_avg = (- 42 m/s) / 1.5 sec

A_avg = - 28 m/s²

Notice, the negative sign, indicating the object slowed down.