A ball hits a vertical wall horizontally at 10m/s bounces back at 10 m/s [JIPMER 1999]

• A.          There is no acceleration because \[10\,\frac{m}{s}-\,10\frac{m}{s}=0\]  
• B.          There may be an acceleration because its initial direction is horizontal
• C.          There is an acceleration because there is a momentum change
• D.          Even though there is no change in momentum there is a change in direction. Hence it has an acceleration