To solve the problem, we need to calculate the kinetic energy of a particle given its mass and velocity.
- Kinetic energy (KE) is the energy possessed by a body due to its motion.
- The formula to calculate kinetic energy is:
\[
KE = \frac{1}{2} m v^2
\]
where:
\( m \) = mass of the particle (in kg)
\( v \) = velocity of the particle (in m/s)
- Mass, \( m = 2 \, \text{kg} \)
- Velocity, \( v = 3 \, \text{m/s} \)
\[ KE = \frac{1}{2} \times 2 \times (3)^2 = 1 \times 9 = 9 \, \text{Joules} \]
The kinetic energy of the particle is 9 Joules.
A bob of mass \(m\) is suspended at a point \(O\) by a light string of length \(l\) and left to perform vertical motion (circular) as shown in the figure. Initially, by applying horizontal velocity \(v_0\) at the point ‘A’, the string becomes slack when the bob reaches at the point ‘D’. The ratio of the kinetic energy of the bob at the points B and C is: 
Three friends, P, Q, and R, are solving a puzzle with statements:
(i) If P is a knight, Q is a knave.
(ii) If Q is a knight, R is a spy.
(iii) If R is a knight, P is a knave. Knights always tell the truth, knaves always lie, and spies sometimes tell the truth. If each friend is either a knight, knave, or spy, who is the knight?