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Question
The position time graph of a body of mass 2 kg is as given in figure. What is the impulse on the body at t = 0 s and t = 4 s.
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Solution
Given, the mass of the body (m) = 2 kg
From the position-time graph, the body is at x = 0 when t = 0, i.e., body is at rest.
∴ Impulse at t = 0, s = 0, is zero
From t =0 s to t = 4 s, the position-time graph is a straight line, which shows that body moves with uniform velocity.
Beyond t = 4 s, the graph is a straight line parallel to time ads, i.e., the body is at rest (v = 0).
The velocity of the body = slope of a position-time graph
= tan θ = `3/4` m/s
impulse (at t = 4 s) = change in momentum
= mv – mu
= m(v – u)
= `2(0 - 3/4)`
= `- 3/2` kg-m/s = – 1.5 kg-m/s
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