Laws of Motion - Result Question 28

28. The mass of a lift is $2000 kg$. When the tension in the supporting cable is $28000 N$, then its acceleration is:

[2009]

(a) $4 ms^{-2}$ upwards

(b) $4 ms^{-2}$ downwards

(c) $14 ms^{-2}$ upwards

(d) $30 ms^{-2}$ downwards

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Answer:

Correct Answer: 28. (a)

Solution:

(a) Net force, $F=T-mg$

$2000 a=28000-20000=8000$

$a=\frac{8000}{2000}=4 ms^{-2} \uparrow$