A spherical body of mass 2 kg starting from rest acquires a kinetic energy of 10000 J at the end of 5th second. The force acted on the body is ________ N. Numerical answer type. Work it out, then open the answer.

Answer: 40. 1/2mv² = 10000 ⇒ v² = (2 × 10000)/(2) = 10⁴, so v = 100 m/s at t = 5 s. From rest, a = v/t = 100/5 = 20 m/s² F = ma = 2 × 20 = 40 N

A spherical body of mass 2 kg starting from rest acquires a kinetic… | JEE Main 2023 (24 Jan, Shift 1)

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Work-Energy Theorem

A spherical body of mass 2 kg starting from rest acquires a kinetic energy of 10000 J at the end of $5^{\text{th}}$ second. The force acted on the body is ________ N.

Numerical answer type. Work it out, then open the answer.

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Answer: 40

$\frac{1}{2}mv^2 = 10000 \Rightarrow v^2 = \frac{2 \times 10000}{2} = 10^4$ , so $v = 100\text{ m/s}$ at $t = 5\text{ s}$ .
From rest, $a = \frac{v}{t} = \frac{100}{5} = 20\text{ m/s}^2$
$F = ma = 2 \times 20 = 40\text{ N}$

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