IIT JEE , AIEEE Forum - Physics , Mechanics

Werewolf

A plank with a uniform sphere placed on it resting on a smooth horizontal plane.Plank is pulled to the right by a constant force F .If the sphere does not slip over the plank.Which of the following is incorrect?

(a) Acceleration of the center of sphere is less than that of plank
(b) Work done by friction acting on the sphere is equal to its total kinetic energy.
(c) Total kinetic energy of the system is equal to the work done by force F.
(d) None of the above

rathin_123

from work & enrgy rule it's (B)

Werewolf

rathin the question says which one is INCORRECT

rtiit

edit:::::::::::::

Pavis

i think a ) is incorrect.wat is the answer

ananth_patri

is it B as incase of pure rollin the work done by fric is zero..

rathin_123

i know.then what is right?if you know then tell plz.

ananth_patri

wat is the answer....??

iit009

i think a) option should be correct.am i correct?

Werewolf

The answer is D ....

SCIENTIST135

AS SPHERE IS NOT SLIPPING, THAT MEANS IT IS ROLLING. CONSTANT FORCE MEANS A CONSTANT ACC IS ACTING. HENCE ACC OF SPHERE WRT PLANK IS SAME AS THAT OF PLANK WRT SPHERE. HENCE (A) IS INCORRECT.

B OPTION IS TRUE BECAUSE FRICTION IS ONLY PROVIDING KE TO THE SPHERE WRT PLANK.

C IS ALSO TRUE.

priyesh

since sphere is not slipping on the plank hence acc. of plank = acc. of the bottomost point.

now let the acc. of centre of sphere be acm

hence acm + Ralpha = acc. of bottomost point = acc. of plank

hence acm = acc.of plank - Ralpha

hence a) is correct

b) is correct as friction is the only force causing movement of the sphere

c) is correct as only external force is F

hence ans is D)

ananth_patri

How is my expln wrong???incase of pure rolling the workdone by fri is zero so.....B is wrong???!!!pzl expl me clearly....

SCIENTIST135

PRIYESH IS DEFINETLY TRUE

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