A 2 kg particle moves with a velocity of 3 m/s in the x-direction. Write the expression for its kinetic energy and calculate its numerical value.

medium 3 marks Class 11 · Physics · Work Energy and Power

Answer

9 J

The correct answer is 9 J — Therefore the kinetic energy is $9 J$ .

Step-by-step solution

Write the kinetic energy formula: $K E = \frac{1}{2} m v^{2}$ .
Substitute $m = 2 kg$ and $v = 3 m/s$ into the formula: $K E = \frac{1}{2} \times 2 \times (3)^{2}$ .
Simplify: $K E = 1 \times 9 = 9$ .
Therefore the kinetic energy is $9 J$ .

Common mistake: Forgetting the factor

\frac{1}{2}

or miscalculating

v^{2}

Concept tested: Kinetic Energy of a particle