Newtons Third Law and Force Imbalance

AI Thread Summary
In the discussion about Newton's Third Law, participants analyze a scenario where a 140 kg man pushes a 90 kg man, resulting in the smaller man moving backward. The consensus is that while the forces exerted by both men are equal and opposite, the smaller man's movement occurs because the net force acting on him is greater than zero, indicating that friction has been overcome. The larger man remains stationary due to a net force of zero acting on him. Clarification is provided that the wording of the problem could be improved for better understanding. Overall, the principles of Newton's laws are upheld, illustrating the relationship between action, reaction, and motion.
narutodemonki
Messages
7
Reaction score
0

Homework Statement


1.A 140 kg man pushes a 90 kg man. They are first motionless, as they push larger man moves smaller one backwards.
which statement is correct.
a)forces are always equal
b) larger wrestles always exerts larger force
c)when they are motionlesss forces are equal but as they start to move larger man exerts a larger force on smaller man exert man on him.


The Attempt at a Solution


According to Newtons third law..every action force has an equal but pposite reaction force
..in that case the answer would be a)
but than why is the smaller man moving back is it because the force of friction on the man has been overcome?
 
Physics news on Phys.org
According to Newtons third law..every action force has an equal but opposite reaction force
..in that case the answer would be a)
Yes, you are correct, but I think the problem should have been worded better: the force exerted by the larger man on the smaller man is always equal (and opposite) to the force exerted by the smaller man on the larger man.
but than why is the smaller man moving back is it because the force of friction on the smaller[/color] man has been overcome?
Yes, the net force on the smaller man is greater than zero, so the smaller man accelerates, per Newton 2; the net force on the larger man is zero, so the larger man does not move, per Newton 1.
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top