1. The problem statement, all variables and given/known data 2. Relevant equations 3. The attempt at a solution Assuming the right direction is positive, it hits the wall and reaches point 2, so to get back to point 1, it's in a negative direction, so it should be MINUS 4m so option A but the correct answer is B?? Or is it to do with total displacement? In which case would that be zero then? Since it hits the wall then comes back to point 1 anyway.