Question

In Lecture 24(Rolling Motion and Gyroscopes) Professor Lewin found out the acceleration of a cylinder rolling on an inclined plane to be 2gsinB/3(B is angle of inclination).
To demonstrate this, I did an experiment at home. I took a wooden plank, set it to an inclination of almost 3 degrees, and rolled a 50 g cylinder from it. I recorded the time, and the acceleration i found(s=at^2/2) was nowhere close to 2gsinB/3.
Instead, it was very close to gsinB, which would have been the case if there was no rolling.
Where could I have gone wrong? The plank was not so smooth

Answer 1

yes the acceleration is uniform so u can apply 1/2*atsquare formula:

it is such a beautiful fact that whenever professor walter lewin does an experiment he takes uncertainities with them as a perfect experiment cannot be done

i think u could have gone wrong with time measurement and
also u could have given the body some initial velocity when u kept it on the inclined plane so the 2/3=0.667 times the answer could have gone appart
as the difference between gsinB and 2/3*sinB is minimal

also this criterion plays: the co-efficient of friction changing (between the first few milli seconds because of kinetic and static co-efficient being different)

Answer 2

Thank you, I knew that you would be the only one who would reply to this! I will repeat the experiment, considering your points

Answer 3

:)

Answer 4

Hurray! I repeated the experiment and got the time almost exactly as the time I had predicted! It was only an error would be 0.3%. Professor Walter Lewin would be proud! ;)
Thanks again, salini

Answer 5

:) i am proud of u......

Answer 6

That's so nice of you...merci(thanks!!