Question

An elevator and its load have a total mass of $800 \, kg$ . The elevator is originally moving downwards at $10 \, m \, s^{- 1}$ , it slows down to stop with constant acceleration in a distance of $25 \, m$ . Find the tension $T$ in the supporting cable while the elevator is being brought to rest. (Take $g=10 \, m \, s^{- 2} \, $ )

• A. $8000N$
• B. $1600N$
• C. $9600N$
• D. $6400N$

Answer 1

Answer: (C)

As the elevator is going down with decreasing speed, so acceleration is upward duration, Let it is $a$


$T-800g=800a,$
$T=800\left(\right.g+a\left.\right)$
From $v^{2}=u^{2}-2as$ ,
$\therefore \, a=2 \, m \, s^{- 2}$
$\therefore \, T=800\left(10 + 2\right)$ ,
$\therefore \, T=9600$ N