A ball hits a vertical wall horizontally at $10m/s$ bounces back at $10 m/s$
A ball hits a vertical wall horizontally at $10m/s$ bounces back at $10 m/s$
There is no acceleration because $10\,\frac{m}{s} - \,10\frac{m}{s} = 0$
There may be an acceleration because its initial direction is horizontal
There is an acceleration because there is a momentum change
Even though there is no change in momentum there is a change in direction. Hence it has an acceleration
A ball hits a vertical wall horizontally at $10m/s$ bounces back at $10 m/s$
As the ball bounces back with same speed so change in momentum $= 2 mv$
and we know that force = rate of change of momentum
i.e. force will act on the ball so there is an acceleration.