Question

A man sits in a machine which generates acceleration five times more than the acceleration due to gravity. If the mass of the man is 80 kg, what is his weight? Take g = 10 ms⁻².

Answer 1

Mass of the man = m = 80 kg
Acceleration due to gravity = g=10 ms⁻²
Acceleration generated by the machine
= a = 5 g= 5 × 10 = 50 ms⁻²
Case I:
When machine accelerates downward
Effective weight of the man = mg – ma = m(g − a)
= 80 (50 − 10) = 3200 N
Case II: 
When the machine accelerates upward
Effective weight of man = mg + ma = m (g + a)
= 80 (10 + 50)
= 80 × 60
= 4800 N