The position-time graph of a body of mass 0.04 kg. Suggest a suitable physical context for this motion. The time between two consecutive impulses received by the body, the magnitude of each impulse is

The graph could be representing a ball rebounding between two walls separated by 2 cm with a constant velocity in free space. After receiving the impulse ball changes its direction. Hence time between two impulses is 2 seconds. 
velocity = time$\times$displacement ​=$\frac{2\times {10}^{-2}}{2}$ = 0.01 m/s
Initial momentum, 
mu = $0.04\times {10}^{-2}$ kgm/s 
Final momentum, 
mv = $-0.04\times {10}^{-2}$ kgm/s 
∴ Change in momentum = $0.08\times {10}^{-2}$kgm/s