State the conservation of momentum principle.
Ball X has a mass of $240\,\text{g}$ and travels in a straight line over a horizontal frictionless surface with an initial speed of $16\,\text{m s}^{-1}$. It then collides with a stationary ball Y of mass $480\,\text{g}$. After the collision, ball X is stationary, as shown in Fig. 2.1.
Show that the speed $v$ of ball Y after the collision is $8.0\,\text{m s}^{-1}$.
Calculate the change in the total kinetic energy $\Delta E_{K}$ of the balls caused by the collision.
In (b), the collision lasts for $2.0\,\text{ms}$. Assume that the contact force between the balls remains constant throughout this interval.
Determine both the magnitude and the direction of the force exerted on ball X by ball Y during the collision.
Compare the magnitude and direction of the force exerted on ball Y by ball X during the collision with the answers in (c)(i). No extra calculations are needed.