Final answer:
In physics, the amount of work done is calculated as the product of force and displacement.
Step-by-step explanation:
The amount of work done by a man lifting a box depends on the force he applies and the distance over which he moves the box. The force applied by the man is equal to the weight of the box, which is the mass of the box times the acceleration due to gravity (50 kg × 9.8 m/s2 = 490 N). However, if the man is holding the box at arm's length and not moving it vertically, then the vertical displacement is zero.
According to the formula for work, W = F × d × cos(θ), where W is work, F is the force applied, d is the displacement, and θ is the angle between the force and displacement vectors, no work is performed on the box in terms of physics, because the displacement (d) is zero. Therefore, the correct answer to the amount of work done is a) Zero.