A porter lifts luggage of 20 kg from the ground onto his head, 2 m above the ground. Calculate the work done on the luggage (take g = 10 ms⁻²).

1. Work done against gravity = mgh. 2. Substitute m = 20 kg, g = 10 ms⁻², h = 2 m. 3. W = 20 × 10 × 2 = 400 J. _Source: RRB Group D CEN-02/2018 PYQ, Q.84._