Q. Two boys of masses 10 kg and 8 kg are moving along a vertical rope, the former climbing up with acceleration of 2 $ms^{- 1}$. 2 while later coming down with uniform velocity of 2 $ms^{- 1}$. Then tension in rope at fixed support will be(Take $g = 10ms^{- 2}$)

A) 200 N
B) 120 N
C) 180 N
D) 160 N
Explanation

(b) Since, $m_{2}$ moves with constant velocity
[image:7_image136.emf]
$\therefore\ f_{2} = m_{2}g$
$f_{2} = 8 \times 10 = 80$N
Since, boy of mass $m_{1}$ moves with acceleration $a = 2ms^{- 2}$ in upward direction
[image:7_image137.emf]
$\therefore f_{1} = m_{1}g = m_{1}a$
$\therefore f_{1} = m_{1}g = m_{1}a$
$= 10 \times 10 + 10 \times \ = 120$ N

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.