The tension in the cable supporting a lift moving upwards is twice the tension when the lift moves downwards. What is the acceleration of the lift?
- A. g/4
- B. g/3
- C. g/2
- D. g
Answer: B. g/3
Explanation: $T_{up} = m(g+a)$, $T_{down} = m(g-a)$. $m(g+a) = 2m(g-a) \Rightarrow g+a = 2g-2a \Rightarrow 3a = g \Rightarrow a = g/3$.