Question

A 5 kg object moving to the right at 4 m/s collides inelastically with a 5 kg object

moving to the left at 4 m/s. The final velocity of both objects will be​

Answer 1

The linear momentum of a particle with mass m moving with velocity v is defined as

p = mv (7.1)

Linear momentum is a vector . When giving the linear momentum of a particle you must

specify its magnitude and direction. We can see from the definition that its units must be

kg·m

s

. Oddly enough, this combination of SI units does not have a commonly–used named so

we leave it as kg·m

s

!

The momentum of a particle is related to the net force on that particle in a simple way;

since the mass of a particle remains constant, if we take the time derivative of a particle’s

momentum we find

dp

dt = m

dv

dt = ma = Fnet

so that

Fnet =

dp

dt (7.2)