## exploringphysics 2 years ago A SMALL BOB IS IN CONTACT WITH THE WEDGE AND THE ROD HOLDING THE BOG IS LIGHT AND VERTICALLY INITIALLY. NOW THE BOB IS DISPLACED AND THE SYSTEM STARTS MOVING. THE BOB AND WEDGE LOOSE CONTACT WHEN ANGLE BETWEEN HORIZONTAL AND ROD IS 30. FIND THE ACCELERATION OF THE WEDGE AT THIS INSTANT

1. exploringphysics

ALSO FRICTIN IS ABSENT SEE THIS IMAGE |dw:1355853151871:dw|

2. shubhamsrg

*

3. shubhamsrg

@Vincent-Lyon.Fr

4. Robinronaldo

I don't see the wedge in the image. I just see bob, rod and a wooden square block

5. exploringphysics

the square box ,[you say] is a wedge only. just solve this .....

6. Robinronaldo

can you share your progress on the question?

7. exploringphysics

I wrote equations for motion using newton laws and tried to put N(between) wedge and bob to be zero . this gives me the tangential acc. of bob as gcos@ [@ is angle btw horizontal and rod. here it's 30]. But what is acc. for the wedge??????|dw:1356000602528:dw|

8. Robinronaldo

give me some time, I am on it...

9. Robinronaldo

Here you go! Let me know what you think?

10. exploringphysics

NO the radial acc. can't be zero . the particle still rotates and need mw^2r towards the hinge......... :( try anything else

11. Saikam

acceleration of the wedge is ZEROOOOOOOWWWW . speed is not. because at the instant the bob loses contact with the wedge, who else would apply a force on it? no body! so acceleration =0

12. shubhamsrg

@Saikam accn =0 after that instant is history. But we are asked about accn at that very instant.

13. Saikam

wat is the force required to lift a 4kg block off the floor ? take g = 10 m/s2

14. Saikam

we generally say it is 40N . but if u apply 4N, the net force would still be zzero and the block should not move. actually we need a force just greater than 40N . But we usually call it 40N. This is the same case. the acceleration would be just greater than 0. but we can say it is =0

15. Vincent-Lyon.Fr

Saikam is right: at instant of separation, contact force becomes zero, so acceleration of wedge is 0 too.