Physics - Center of Mass Question with Solution | TestHub

Let the first mass be m and initial speed u.

$$\frac{1}{2}m{u}^2=3\mathrm{J}$$

At maximum compression both masses move together with the centre-of-mass speed.

$$v=\frac{mu}{m+2m}=\frac{u}{3}$$

$$K_{\min }=\frac{1}{2}(3m)(u/3{)}^2=\frac{1}{3}\left(\frac{1}{2}m{u}^2\right)=1\mathrm{J}$$

$$U_{\max }=3-1=2\mathrm{J}$$

During the elastic collision, momentum and total energy are conserved. A, B and C are correct.