Question

: Two boxes, A and B, are connected to each end of a
light vertical rope, as shown in Figure below. A constant
upward force is applied to box A. Starting from rest, box B
reaches a velocity of 6m/s in 9m of displacement. If the
mass of block A and B are respectively 5Kg and 3Kg, (a)
What is the applied upward force? (b) What is the tension in
the massless rope? (see fig below)

Answer 1

Answer:

Let acceleration of man with respect to ground is a

0

and acceleration of block is a.

here, a+a

0

=g/6 or a

0

=g/6−a

From FBD of man, ma

0

=T−mg or m(g/6−a)=T−mg

or T+ma=7mg/6...(1)

From FBD of block A:

2

m

a=T−

2

m

g or T−ma/2=mg/2..(2)

(1)−(2)⇒3ma/2=2mg/3 or a=

9

4g

from (2), T=mg/2+(m/2)(4g/9)=

18

13mg