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The position-time graph of a body of mass 2 kg is given in Figure. What is the impulse on the body at t = 0 s and t = 4 s?

Answers (1)

 Given: mass(m) = 2kg. 

Let v1 be the initial velocity, v1 = 0, from the above graph t ≥ 0 to t ≤ 4, viz., a straight line. Hence, the velocity of the body will be constant.

v_{2} = \frac{3}{4} = 0.75 m/s

At t ≥ 4, The slope of the graph is zero; hence, the velocity v3 = 0.

Now, impulse =F .t = \frac{d\overrightarrow{p}}{dt} .dt = d\overrightarrow{p}

We know that impulse is the change in momentum. so,

Impulse at t = 0;

                = 2[0.75 – 0] = 1.50 kg ms-1

Impulse at t = 4;

= m (v_{3} - v_{2}) =2 [0 – 0.75] = -1.50 kg ms-1

Therefore, at t = 0, the impulse increases by +1.5kg ms-1, and At t = 4, the impulse decreases by 1.5 kg ms-1.

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