the normal. This answer is wrong. The force on the wall is normal to the wall in both cases. How to find the force on the wall?
The trick is to consider the force (or impulse) on the ball due to the wall using the second law, and then use the third law to answer (i). Let u be the speed of each ball before and after collision with the wall, and m the mass of each ball. Choose the x and y axes as shown in the figure, and consider the change in momentum of the ball in each case : Case (a) initial initial x mu p