Lectures in Physics has been derived from Benjamin Crowell's Light and Matter series of free introductory textbooks on physics. See the editorial for more information....



An accelerating bus

A VW bus with a mass of 2000 kg accelerates from 0 to 25 m/s (freeway speed) in 34 s. Assuming the acceleration is constant, what is the total force on the bus?

We solve Newton's second law for Ftotal = ma, and substitute Dv/Dt for a, giving

Ftotal = mDv/Dt
= (2000 kg)(25 m/s - 0 m/s)/(34 s)
= 1.5 kN .



Last Update: 2006-Nov-21