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?
Between x = 0 and x = 2 cm, ball will be rebounding between two walls.
After every 2 s,
Magnitude of the impulse received by the ball = 0.08 × 10–2
The given graph shows that a body changes its direction of motion after every 2 s.
Physically, this situation can be visualized as a ball rebounding to and fro between two stationary walls situated between positions x
= 0 and x
= 2 cm.
The slope of the position-time graph reverses after every 2 s, the ball collides with a wall after every 2 s.
Therefore, ball receives an impulse after every 2 s.
Mass of the ball, m
= 0.04 kg
The slope of the graph gives the velocity of the ball.
Using the graph,
Initial velocity, (u
Velocity of the ball before collision, u
Velocity of the ball after collision, v
Here, the negative sign arises as the ball reverses its direction of motion.
Magnitude of impulse = Change in momentum
= | mv - mu
= | 0.04 (v
= | 0.04 (-10-2
= 0.08 × 10-2