A) \[\frac{{{w}_{1}}+{{w}_{2}}}{2}\]
B) \[\frac{{{w}_{1}}-{{w}_{2}}}{2}\]
C) \[2{{w}_{1}}\]
D) \[2{{w}_{2}}\]
Correct Answer: A
Solution :
When lift moves up with constant acceleration a, then \[{{w}_{1}}-mg=ma\] ?(i) When lift moves down with constant acceleration a, then \[mg-{{w}_{2}}=ma\] ?(ii) From Eqs. (i) and (ii), we get \[{{w}_{1}}+{{w}_{2}}=2mg\] ?(iii) When lift moves up with constant speed, its acceleration is zero. So, \[w-mg=0\] or \[w=mg\] (iv) From Eqs. (iii) and (iv) \[{{w}_{1}}+{{w}_{2}}=2w\] or\[w=\frac{{{w}_{1}}+{{w}_{2}}}{2}\]You need to login to perform this action.
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