What is the amount of work that a crane needs to do to lift bricks weighing 100 kg to a height of 20 m?

Work in physics can be found by the formula A = F * s, where A is the work done by the body, F is the applied force, s is the path.
1) F = m * g = 100 kg * 10 N / kg = 1000 N (where g is the acceleration of gravity).
2) A = F * s = 1000 N * 20 m = 20,000 J = 20 kJ (since one kilojoule is equal to one thousand joules).
Answer: A = 20 kJ.