The figure shows the position - time (x−t) graph of one-dimensional motion of a body of mass 0.4 kg . The magnitude of each impulse is
(A)0.4 Ns
(B)0.8 Ns✓ Correct
(C)1.6 Ns
(D)0.2 Ns
Answer: (B)
Solution
The position-time graph is built from straight segments, so the body moves at a constant speed equal to the slope, reversing its velocity at each kink where an impulse acts. Reading the slopes, the speed is 1 m/s, with the velocity turning from +1 m/s to −1 m/s. The impulse equals the change in momentum, J=mΔv=0.4×(1−(−1))=0.4×2=0.8 N s in magnitude.
JEE Main · 2010 · 11 Apr 2010 · Offline · Single correct option