Physics

Problem

In an isolated two-object collision on a frictionless, horizontal surface, the system’s total linear momentum is

\vec p_{\text{tot}}

. Which statement about the components of

\vec p_{\text{tot}}

is always true? a) The magnitude of

\vec p_{\text{tot}}

is conserved, but its direction (and thus its individual components) can change during the collision. b) Each component (

x

and

y

) of

\vec p_{\text{tot}}

remains constant throughout the collision. c) Only the

x

-component of

\vec p_{\text{tot}}

is conserved because the initial motion is along the

x

-axis. d) Each component of

\vec p_{\text{tot}}

is conserved only if the collision is perfectly elastic; otherwise they can change.