Figure 5.17 shows the position-time graph of a body of mass 0.04 kg. Suggest a suitable physical context for this motion. What is the time between two consecutive impulses received by the body? What is the magnitude of each impulse?
Given:
Mass of body = 0.04 kg
From the graph (position- time) we observe that, a body is moving linearly to a displacement of 2 cm, then it comes back to 0 position, each cycle consumes 4 seconds. This graph might represent a ball bouncing between two walls located 2 cm apart. Ball starts at time 0 from position x = 0 with some velocity, after 2 seconds it reaches the second wall at a distance of 2 cm, then bounces back to the zero position in next 2 seconds.
We can observe that after every two seconds the ball is changing direction, so we can conclude that it strikes the walls every two seconds, so impulse is imparted to the ball every 2 seconds.
We know that,
Impulse = Change of momentum
→ I = final momentum – initial momentum
→ I = mv- mu …(1)
Where,
M = mass of body
v = velocity of body after collision with wall
u = velocity of body before collision with wall
Velocity of ball can be found as the slope of the curve,
i.e. 
…(2)
Where, v = velocity
x0 = initial displacement in metres
x1 = final displacement in metres
t0 = time at beginning of event
t1 = time at final displacement
By putting the values in equation (2),
→ v = 10-2 ms-1
Initial velocity, u is also the same but with a negative sign,
u = -10-2 ms-1
By putting the values in equation (1) ,
I = |(0.04 kg× 10-2ms-1)- (0.04 kg× (-10-2ms-1))
I = 0.08× 10-2Kg ms-1
The magnitude of impulse is 0.08× 10-2Kg ms-1.