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PhysicsJEE Main 21 Jan 2026, Shift 1·Q6·MCQ·Moderate

Newton's Laws of Motion · Newton's laws

A 4 kg mass moves under the influence of a force F⃗=(4t3i^−3tj^)\vec F = (4t^3\hat i - 3t\hat j) N where tt is the time in second. If mass starts from rest at the origin at t=0t = 0, the velocity and position after t=2t = 2 s will be:
  1. (1)v⃗=3i^+32j^,r⃗=65i^+j^\vec v = 3\hat i + \dfrac32\hat j,\quad \vec r = \dfrac65\hat i + \hat j
  2. (2)v⃗=4i^−32j^,r⃗=85i^−j^\vec v = 4\hat i - \dfrac32\hat j,\quad \vec r = \dfrac85\hat i - \hat j
  3. (3)v⃗=4i^+52j^,r⃗=85i^+2j^\vec v = 4\hat i + \dfrac52\hat j,\quad \vec r = \dfrac85\hat i + 2\hat j
  4. (4)v⃗=4i^−32j^,r⃗=65i^−j^\vec v = 4\hat i - \dfrac32\hat j,\quad \vec r = \dfrac65\hat i - \hat j
We corrected a printing error in the original paper

Assumption “from rest” added; the source leaves it unstated (“starts from origin at t=0t = 0”).

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