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Two blocks each of mass 2kg and 5kg are connected by a string through a massless smooth pulley. a force of 50N is applied on pulley in up direction. find the accln. of 5kg block?

dhwanitmunshi

the acceleration of the 5 kg block would be zero

savvej

5m/s²

sriram123

weight=9.8*5=49n
t=50n
t-mg=ma
a=1/5 m/s2

sailesh_07

savvej can u explain to me y d acc is 5m/s^2

savvej

on the pulley
f-2t=-(since pulley is massless)
.:f=2t
.:t=25
for 5kg block
50-25=5a
.:a=5m/s²

sailesh_07

thanx for the reply dude!!

shohitaa

hey savvej can u plz tell me y havent u taken into consideration the accn of the pulley coz if a force is being applied on it then it will follow the eqn f=ma

so using that concept v can say that the

acc of block of mass 5 =a-a'(a' being the accn of the pulley)
acc of block of mass 2= -a-a'
where a is the accn wrt earth
so
5g-t=5(a-a')
t-2g=2(-a-a')

f=m(of system)a'
therefore :50=(5+2)a
solving the 3 eqns. v get the ans.
plz tell me if i am correct'

Betu

i beg to differ
2T= 50 assumes pulley is fixed, which is not given..

Also, by the logic os savej, the acceleration of 2 Kg block will 12.5 m/s2..!!! which is impossible as the pulley is .smooth.

i think the problem is slightly poorly worded OR incomplete..

Betu

shohitaa,
you seem to have got some hang of the problem...
only problem is if whole system is accelerating with a'...weight will not be m.g...
it wiil be mg-ma' or.. mg+ma' depending upon the direction of a'..

ivar

It is 4m/s

krishna.gopal

Savvej has given perfect answer. And Betu we can write 50-2t = 0 for pully because it is mass less so F=ma=0*a=0

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