A body of mass 4 kg is placed on a plane at a point P having… | JEE Main 2025 (28 Jan, Shift 2)

Q7JEE Main 2025 · 28 JAN · SHIFT 2Medium

Power

A body of mass 4 kg is placed on a plane at a point $P$ having coordinates $(3, 4)\text{ m}$ . Under the action of force $\vec{F} = (2\hat{i} + 3\hat{j})\text{ N}$ , it moves to a new point Q having coordinates $(6, 10)\text{ m}$ in 4 sec. The average power and instantaneous power at the end of 4 sec are in the ratio of:

Show answer and solution

Answer: (d)

Displacement $\vec{s} = (6-3)\hat{i} + (10-4)\hat{j} = 3\hat{i} + 6\hat{j}$ m.
$W = \vec{F} \cdot \vec{s} = 6 + 18 = 24\text{ J}$ , so $P_{avg} = \dfrac{24}{4} = 6\text{ W}$ .
$\vec{a} = \dfrac{\vec{F}}{m} = 0.5\hat{i} + 0.75\hat{j}$ ; from rest $\vec{v} = \vec{a}t = 2\hat{i} + 3\hat{j}$ m/s at 4 s.
$P_{inst} = \vec{F} \cdot \vec{v} = 4 + 9 = 13\text{ W}$
So the answer is (d) $6:13$ .

Report a mistake

More questions on Power

A body of mass 1 kg begins to move under the action of a time dependent force F = (ti +…MHT CET 2025 (22 Apr, Shift 1)
An object of mass 1000 g experiences a time dependent force F = (2ti + 3t²j)N. The power…JEE Main 2025 (7 Apr, Shift 1)
A sand dropper drops sand of mass m(t) on a conveyer belt at a rate proportional to the…JEE Main 2025 (29 Jan, Shift 2)
A body of mass 1 kg starts from rest and moves with uniform acceleration. In 2 seconds…MHT CET 2024 (15 May, Shift 1)
At any instant of time t, the displacement of any particle is given by 2t - 1 ( SI unit)…NEET 2024
A body is moving unidirectionally under the influence of a constant power source. Its…JEE Main 2024 (5 Apr, Shift 2)
The power (P) is supplied to a rotating body having moment of inertia ' I ' and angular…MHT CET 2024 (16 May, Shift 1)
A body of mass 2 kg begins to move under the action of a time dependent force given by F…JEE Main 2024 (31 Jan, Shift 2)

Power question from JEE Main 2025 (28 Jan, Shift 2)

More questions on Power