A man, of mass 60 kg, is riding in a lift. The weight of the man, when the lift is accelerating upwards and downwards at 2 ms -2 are respectively (taking g=10 ms -2 )

Question

A man, of mass 60 kg, is riding in a lift. The weight of the man, when the lift is accelerating upwards and downwards at 2 ms -2 are respectively (taking g=10 ms -2 ) (A) 720 N and 480 N (B) 480 N and 720 N (C) 600 N and 600 N (D) None of these

Tardigrade Admin · Accepted Answer

When the lift is accelerating upwards with constant acceleration

a

,
then Weight

w = m (g + a)

= 60 (10 + 2) = 60 \times 12 = 720 N

When the lift is accelerating downwards at the rate of

a

,
then Weight

w = m (g - a)

= 60 (10 - 2) = 60 \times 8 = 480 N

Q. A man, of mass 60kg, is riding in a lift. The weight of the man, when the lift is accelerating upwards and downwards at 2ms−2 are respectively (taking g=10ms−2 )

720 N and 480 N

480 N and 720 N

600 N and 600 N

None of these

When the lift is accelerating upwards with constant acceleration a, then Weight w=m(g+a) =60(10+2)=60×12=720N When the lift is accelerating downwards at the rate of a, then Weight w=m(g−a) =60(10−2)=60×8=480N

Q. A man, of mass $60 k g$ , is riding in a lift. The weight of the man, when the lift is accelerating upwards and downwards at $2 m s^{- 2}$ are respectively (taking $g = 10 m s^{- 2}$ )

When the lift is accelerating upwards with constant acceleration $a$ ,
then Weight $w = m (g + a)$
$= 60 (10 + 2) = 60 \times 12 = 720 N$
When the lift is accelerating downwards at the rate of $a$ ,
then Weight $w = m (g - a)$
$= 60 (10 - 2) = 60 \times 8 = 480 N$