Introduction:
When a body falls from rest, it gains kinetic energy due to the acceleration caused by gravity. This acceleration is represented by the value of g, which is 10 m/s^2 in this case. To calculate the kinetic energy of the body after 2 seconds, we can use the formula for kinetic energy.

Formula:
The formula for kinetic energy is given by K.E. = 1/2 * m * v^2, where K.E. is the kinetic energy, m is the mass of the body, and v is the velocity of the body.

Calculations:
Given:
- Mass of the body (m) = 2 kg
- Acceleration due to gravity (g) = 10 m/s^2
- Time (t) = 2 seconds

To find the velocity (v) of the body after 2 seconds, we need to use the equation of motion: v = u + gt, where u is the initial velocity.

Since the body is falling from rest, the initial velocity (u) is 0 m/s. Therefore, we can substitute the values into the equation:

v = u + gt
v = 0 + (10 * 2)
v = 20 m/s

Now that we have the velocity of the body after 2 seconds, we can calculate the kinetic energy using the formula:

K.E. = 1/2 * m * v^2
K.E. = 1/2 * 2 * (20^2)
K.E. = 1/2 * 2 * 400
K.E. = 400 J

Conclusion:
The kinetic energy of the body after falling for 2 seconds is 400 J (joules).