question_answer

A lift of mass 1000 kg is moving upwards with an acceleration of \[1\text{ }m/{{s}^{2}}\]. The tension developed in the string, which is connected to lift is: \[(g=9.8\text{ }m/{{s}^{2}})\]                                 [AIPMT 2002]

A) 9800 N

B) 10800 N

C) 11000 N

D) 10000 N

Correct Answer: B

Solution :

Key Idea: The tension in the string during upward motion increases from weight of life due to its upward acceleration.

When lift moves upward with same acceleration then

\[Tmg=ma\]

or         \[T=m\text{ }(g+a)\]

Given, \[m=1000\text{ }kg,\text{ }a=1\text{ }m/{{s}^{2}},\text{ }g=9.8\text{ }m/{{s}^{2}}\]

Thus,    \[T=1000\text{ }(9.8+1)\]

\[=1000\times 10.8\]

\[=10800\text{ }N\]