Question

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 ___$N$

Answer 1

Correct Answer: 40

The kinetic energy is related to velocity as: \[ \frac{1}{2} m v^2 = \text{KE} \] Substitute the given values (\(m = 2 \, \text{kg}, \, \text{KE} = 10000 \, \text{J}\)): \[ \frac{1}{2} \cdot 2 \cdot v^2 = 10000 \] \[ v^2 = 10000, \quad v = 100 \, \text{m/s} \] The acceleration is found using: \[ v = u + at \] Since the body starts from rest (\(u = 0\)) and reaches \(v = 100 \, \text{m/s}\) in \(t = 5 \, \text{s}\): \[ 100 = 0 + a \cdot 5 \implies a = \frac{100}{5} = 20 \, \text{m/s}^2 \] The force acting on the body is: \[ F = m \cdot a = 2 \cdot 20 = 40 \, \text{N} \]