Question

Q 2.
A man of mass 70 kilogram stands on
weighing scale in a lift which is moving
upward with a uniform speed of 10
m/s. What would be the reading on the
scale in weighing machine?​

Answer 1

Mass of the man, m = 70 kg

Acceleration, a = 0

Using Newton’s second law of motion, we can write the equation of motion as:

R – mg = ma

Where, ma is the net force acting on the man.

As the lift is moving at a uniform speed, acceleration a = 0

∴ R = mg

= 70 × 10 = 700 N

∴ Reading on the weighing scale = 700 / g = 700 / 10 = 70 kg