Question

A body of mass 2 kg is hung on a spring balance mounted vertically in a lift. If the lift moves up with an acceleration equal to the acceleration due to gravity, the reading on the spring balance will be

• A. 2 kg
• B. $(2 \times g)kg$
• C. $(4 \times g)kg$
• D. 4 kg

Answer 1

When lift moves upward then reading of the spring balance, $R = m(g + a) = 2(g + g) = 4g\mspace{6mu} N = 4\mspace{6mu} kg$ [As $a = g$]