Physics - Center of Mass Question with Solution | TestHub

Impulse is defined as the change in momentum. Let the initial direction of the ball be positive. Initial momentum $p_i=m{v}_i$. Final momentum $p_f=m{v}_f$. Given: Mass $m=0.5\text{ kg}$ Initial speed $v_i=10\text{ m/s}$ Rebound speed $v_f=-8\text{ m/s}$ (negative sign indicates opposite direction) Impulse $J=\Delta p=p_f-p_i=m(v_f-v_i)$.$$J=0.5\text{ kg}\times (-8\text{ m/s}-10\text{ m/s})=0.5\times (-18)\text{ Ns}=-9\text{ Ns}$$ The magnitude of the impulse exerted by the wall on the ball is $|-9|=9\text{ Ns}$.