IIT JEE , AIEEE Forum - Physics , Mechanics

maddy12345

A body of mass 15 kg is lying on a frictionless surface that makes an angle of 30⁰ with the ground.Another body of mass 6 kg is put on the previous body.Find the acceleration of the 15 kg body and also the acceleration of the 6 kg body with respect to the 15 kg body ?

Send full solution of the above question. Thank you.

coolank2

The acc of 15 kg block will be ..... 15.g.sin 30 = 7.5g
The acc of 6 kg block will be ..... 6.g.sin 30 = 3g (unless there is friction between the blocks) .....

So the acc of 6 kg block w.r.t. 15 kg block = 3g - 7.5g = -4.5g

imnotserious_2008

force acting downward ||to incline f = 15gsin30+6gsin30
u need to consider them as one system
total mass m =15+6=21
thus acceleration of both the blocks=f/m (if friction is present between the blocks)

relative acceleration=0

if i m wrong then please correct me

imnotserious_2008

post up the correct ans

Ksudha_iit

when u draw the fbd ...you get to know that only one force drives both...the bodies ie their component parallel to the incline all the other forces ...have their components perpendicular to the incline so they do not affect the acceleration...and imnotserious_2008 ...even if u take them as a system you cant tell both of them will travel with same acceleration unless mentioned that friction is present ....and even if friction ...was to be there then it would have been an internal force ..so it would nt have any effect on accleration...so maddy i hope its clear to u....i believe coolank is correct in his concept and dont blame me if his calculation is wrong ....

thank you ..
do rate me if ur doubt was cleared

maddy12345

Sorry to all of you but the actual acceleration of the 15 kg body is 6.33m/square

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