The mass of a lift is $2000 ext{ kg}$. When the tension in the supporting cable is $28000 ext{ N}$, its ac

Question

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

Accepted Answer

1. **Identify Forces:** The forces acting on the lift are the tension ($T$) in the cable acting upwards and the weight ($mg$) of the lift acting downwards.
2. **Compare Forces:** 
   - Tension, $T = 28000 	ext{ N}$.
   - Weight, $W = mg = 2000 	ext{ kg} 	imes 10 	ext{ ms}^{-2} = 20000 	ext{ N}$ (assuming $g \approx 10 	ext{ ms}^{-2}$).
   - Since $T > mg$ ($28000 > 20000$), the net force is acting upwards, meaning the lift accelerates upwards.
3. **Apply Newton's Second Law:** The net force $F_{net}$ equals mass times acceleration ($ma$).
   $$ F_{net} = T - mg = ma $$
   $$ 28000 - 20000 = 2000 	imes a $$
   $$ 8000 = 2000 a $$
4. **Calculate Acceleration:**
   $$ a = \frac{8000}{2000} = 4 	ext{ ms}^{-2} $$
   Direction is upwards.
   (Reference: NCERT Class 11, Physics Part I, Chapter 5, Laws of Motion, Section 5.9 Common Forces in Mechanics).

Step-by-Step Solution

Practice All PHYSICS Questions