Physics 9702 · AS & A Level · Linear momentum and its conservation
Linear momentum and its conservation — practice question
As shown in Fig. 3.1, balls X and Y travel over a horizontal frictionless surface. Ball X begins with velocity $3.0\,\text{m s}^{-1}$ along line AB. Ball Y has mass $2.5\,\text{kg}$ and starts with velocity $9.6\,\text{m s}^{-1}$ at an angle of $60^{\circ}$ to line AB. They collide at point B. After the collision, the two balls remain stuck together and move across the horizontal surface in a direction at right-angles to line AB, as shown in Fig. 3.2.
(a)[2]
Using the momentum components in the direction from A to B, show that ball X has mass of $4.0\,\text{kg}$.
(b)[2]
Calculate the shared speed $V$ of the two balls after the collision.
(c)[2]
Find the difference between the initial kinetic energy of ball X and the initial kinetic energy of ball Y.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “$(m \times 3.0) - (2.5 \times 9.6 \times \cos 60^\circ) = 0$” …