Question 181: Laws of Motion

Question

A person standing on a spring balance inside a stationary lift measures 60 kg. The weight of that person if the lift descends with uniform downward acceleration of 1.8 m/s2 will be ______________ N. [g = 10 m/s2]

Accepted Answer

The apparent weight $W_{	ext{app}}$ of a person in an elevator moving with acceleration is given by:
$$W_{	ext{app}} = m(g - a)$$
where:
$W_{	ext{app}}$ is the apparent weight,
$m$ is the mass of the person,
$g$ is the acceleration due to gravity,
$a$ is the acceleration of the elevator.
Given that the person's mass is 60 kg, the acceleration due to gravity is 10 m/sÃÂ², and the acceleration of the lift is 1.8 m/sÃÂ², we can substitute these values into the formula:
$$W_{	ext{app}} = 60 \, 	ext{kg} 	imes (10 \, 	ext{m/s}^2 - 1.8 \, 	ext{m/s}^2) = 60 \, 	ext{kg} 	imes 8.2 \, 	ext{m/s}^2 = 492 \, 	ext{N}$$
So, the apparent weight of the person when the lift descends with a uniform downward acceleration of 1.8 m/sÃÂ² will be 492 N.

Laws of Motion

A person standing on a spring balance inside a stationary lift measures 60 kg. The weight of that person if the lift descends with uniform downward acceleration of 1.8 m/s2 will be ______________ N. [g = 10 m/s2]

Choose the correct answer: