p = momentum
m = mass
v = velocity
Momentum same direction as velocity
Units: kg·m/s
What is the toy truck’s
momentum?
p = mv
p = (0.14 kg)(1.2 m/s)
p = 0.17 kg·m/s to the right
7.2 - Momentum and Newton's second law
Although you started your study of physics with velocity and acceleration, early physicists such as Newton focused much of their attention on
momentum.
The equation in Equation 1 may remind you of Newton's second law. In fact, it is equivalent to the second law (as we show below) and Newton
stated his law in this form. This equation is useful when you know the change in the momentum of an object (or, equivalently for an object of
constant mass, the change in velocity). This equation as stated assumes an average or constant external net force.Momentum and Newton's second
law
ȈF = net force
p = momentum
t = time
(^146) Copyright 2007 Kinetic Books Co. Chapter 07