A block of mass 5 kg moves along the x-direction subject to the force F = (−20x + 10) N, with the value of x in metre. At time t = 0 s, it is at rest at position x = 1 m. The position and momentum of the block at t = (π /4) s are
Answer key (C) & worked solution
Correct answer: Option C
∴ Particle will perform SHM about with ω = 2 rad/sec ⇒ T = π sec. ∴ Phase covered in second = 90°. Given particle is at rest at x = 1m ⇒ x = 1 is extreme position. In sec, it will be at equilibrium x = 0.5 m and momentum = mω A = 5 × 2 × 0.5 = 5 kg m/s Direction will be towards –ve x.