Physics - Center of Mass Question with Solution | TestHub

Equal masses exchange the normal component at each wall. After wall A: particle$(v,0)$, frame$(0,v)$. In the frame's rest frame it moves at 45° and next hits$t=\frac{a}{v}$ (wall B , at its midpoint) - (A) true. After B: particle (0, 0), frame$(v,v)$; at$t=\frac{3a}{2v}$ frame$\mathrm{KE}=\frac{1}{2}m\left(v^2+v^2\right)=m{v}^2$ - (B) true. The wall order is$\mathrm{A}\to \mathrm{B}\to \mathrm{C}\to \mathrm{D}\to \mathrm{A}$: C follows B, not D - (C) false. The particle rests after B, the frame after D; the cycle repeats with period$\frac{4a}{v}$ - (D) true. Answer: (A), (B), (D)