(a)[2]
State what the principle of conservation of momentum means.
(b)[4]
An object of mass $2m$ moves in a straight line at $5.0\,\text{m s}^{-1}$. It collides with a stationary object of mass $3m$, as shown in Fig. 3.1. After the collision, the object of mass $2m$ travels with velocity $v$ at an angle of $30^{\circ}$ to its original direction of motion. The object of mass $3m$ travels with velocity $w$, also at an angle of $30^{\circ}$, as shown in Fig. 3.2. Using conservation of momentum in two dimensions, calculate the magnitudes of $v$ and $w$.
(c)[3]
An object of mass $4.2\,\text{kg}$ moves in a straight line at a speed of $6.0\,\text{m s}^{-1}$. A constant force brings it to rest over a distance of $0.050\,\text{m}$. Calculate the magnitude of this force.