iran-konkur 2024 Q43

iran-konkur · Other · konkur-riazi_1403_ordibehesht_specialized Work done and energy Work-energy theorem: finding speed or kinetic energy from net work
43-- A football with mass $45\,\text{g}$ is shot from a penalty spot at a speed of $20\,\dfrac{\text{m}}{\text{s}}$ toward the goal and hits the goalkeeper at a speed of $16\,\dfrac{\text{m}}{\text{s}}$. What is the total work done on the ball?
(1) $-10$ (2) $-16.2$ (3) $-32.4$ (4) $-64.8$
\textbf{43--} A football with mass $45\,\text{g}$ is shot from a penalty spot at a speed of $20\,\dfrac{\text{m}}{\text{s}}$ toward the goal and hits the goalkeeper at a speed of $16\,\dfrac{\text{m}}{\text{s}}$. What is the total work done on the ball?

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\noindent (1) $-10$ \hfill (2) $-16.2$ \hfill (3) $-32.4$ \hfill (4) $-64.8$

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