Boy , Table and the Newton

Question

Suppose a boy is trying to stand on a table. If the table can hold upto a particular force, the boy would fall on to earth. If he stands on the table and providing greater force than the table can yield.

Does the table give a reaction force to the boy by newton's third law?

If so, why did he fall down ?

The question is entirely different. Please dont mark questions as duplicate by evaluating some resembling words in them. — Vinayak, Dec 27 '14 at 06:43
the fundamentals are the same. Please put in the effort to do some research before you ask a question here. — pho, Dec 27 '14 at 07:23

Paul · Answer 1 · 2014-12-27T11:29:45.957

1

Does the table give a reaction force to the boy by newton's third law?

If so, why did he fall down ?

the boy was applying a force on the table and table was also applying the same force on the boy.(upward) but since the table was weak hence it was broken. now there is nothing to apply force on the boy upward so simply gravity pulls him down.

EDIT:lets look at a different situation but similar situation to make things clear.

a boy is standing on a elevator and thus he applies a force on the floor of the elevator and the floor is also applying the same force on the boy upward. suddenly the cable broke (this is similar as the breaking of the table) what will happen? the elevator and the boy will now in freefall . In this case because both the boy and the lift are moving downwards with same acceleration 'g' so there are no forces of action and reaction between the boy and the lift. http://hyperphysics.phy-astr.gsu.edu/hbase/elev.html similar happen in the case of boy and the table.

edited Dec 27 '14 at 11:29

answered Dec 27 '14 at 09:04

Paul

3,455

The boy should not fall even if it is so since every time the boy excerts a force the table also excerts the aame force. – Vinayak Dec 27 '14 at 10:56
Edited and please think deeply and open the link. and let me know – Paul Dec 27 '14 at 11:25
When the table breaks, to what is the boy exerting force to ? He is in free fall as suggested. Also the table only breaks when it cannot withstand the boys force, till the breaking point it will give the exact reaction of the boys action. – Gowtham Dec 27 '14 at 11:31

user68504 · Answer 2 · 2014-12-27T07:48:31.300

-1

Analogous to "slope with an angle $\theta$ & a box having mass $M$". When the boy is falling down, the table becomes like a slope and only on the slope surface where the third law works i.e $N=Mg cosθ$, N being the normal force exerted by the slope, rather than $Mg=N$.

edited Dec 27 '14 at 07:48

answered Dec 27 '14 at 03:15

user68504

9

2

Pardon, I didnt get anything – Vinayak Dec 27 '14 at 04:22
@Vinayak I mean the third law still valid in here. It just the reactive force exerted by table is not equal to the weight of the fatty anymore but a part of it. – user68504 Dec 27 '14 at 08:09
So that the law must be revised that for every action there is an equal and opposite reaction only if the object is capable of providing the force – Vinayak Dec 27 '14 at 11:02

Boy , Table and the Newton

2 Answers2