Short Answer 
The total work done by the chain to lift a 2kg block is calculated by first determining the work against gravity, which is 40 Joules, and then adding the kinetic energy imparted to the block, which is 16 Joules. Thus, the total work done by the chain amounts to 56 Joules.
1. Understanding the Forces Involved
In this problem, we need to calculate the total work done by the chain to lift a 2kg block vertically. Two forces are at play: the upward force from the chain and the downward gravitational force. The gravitational force acting on the block can be calculated using the equation: Weight = mass (m) x gravitational acceleration (g).
2. Calculating Work Against Gravity
The work done against gravity when lifting the block is calculated as follows: Work = m x g x h, where m is the mass (2kg), g is the gravitational acceleration (10m/s²), and h is the height (2m). By substituting these values, we get Work against gravity = 2kg x 10m/s² x 2m = 40 Joules.
3. Finding Total Work Done
The total work done by the chain also includes the kinetic energy (KE) imparted to the block as it gains velocity. Kinetic energy can be calculated using the formula: KE = 1/2 x m x v². Here, substituting the values gives us KE = 1/2 x 2kg x (4m/s)² = 16 Joules. Therefore, the total work done by the chain is the sum of work against gravity and kinetic energy: Total Work = 40 Joules + 16 Joules = 56 Joules.