Question

A boy of mass 50 kg is standing on a weighing machine placed at the floor of a lift. The machine reads his weight in newtons. What is the reading of the machine, if the lift is moving Upwards with a uniform Speed of $10\text{ }m{{s}^{-1}}.$ $(g=10m{{s}^{-2}})$

• A. 510 N
• B. 480 N
• C. 490 N
• D. 500 N

Answer 1

Answer: (D)

500 N

Answer 2

Given that mass of boy m = 50 kg Weighing machine is moving upwards with uniform speed, so acceleration of machine will be zero, a = 0. $T-mg=ma$ $T-50g=50\times a$ but $a=0$ $T=50\,g$ $T=50\times 10$ $T=500\,N$